Compound, resin, resist composition and method for producing resist pattern

ABSTRACT

A compound represented by the formula (I). 
     
       
         
         
             
             
         
       
         
         
           
             wherein R 1  represents a hydrogen atom, a halogen atom or a C 1  to C 6  alkyl group that may have a halogen atom; R 2  represents a C 1  to C 12  fluorinated saturated hydrocarbon group; W 1  represents a C 5  to C 18  divalent alicyclic hydrocarbon group; A 1  and A 2  independently represents a single bond or *-A 3 -X 1 -(A 4 -X 2 ) a —; A 3  and A 4  independently represents a C 1  to C 6  alkanediyl group; X 1  and X 2  independently represents —O—, —CO—O— or —O—CO—; a represents 0 or 1; and * represents a bond to an oxygen atom.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending application Ser. No.14/835,102 filed on Aug. 25, 2015, which claims priority under 35 U.S.C.§ 119(a) to Patent Application No. 2014-170762 filed in Japan on Aug.25, 2014 and Patent Application No. 2014-189934 filed in Japan on Sep.18, 2014, all of which are hereby expressly incorporated by referenceinto the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a compound, a resin, a composition, aresist composition and a method for producing the resist pattern.

2. Related Art

A resist composition which contains a resin having the followingstructural unit is described in Patent document of JP 2012-53460A.

SUMMARY OF THE INVENTION

The present invention provides following inventions of <1> to <10>.

<1> A compound represented by formula (I).

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom;

R² represents a C₁ to C₁₂ fluorinated saturated hydrocarbon group;

W¹ represents a C₅ to C₁₈ divalent alicyclic hydrocarbon group;

A¹ and A² each independently represent a single bond or*-A³-X¹-(A⁴-X²)_(a)—;

A³ and A⁴ each independently represent a C₁ to C₆ alkanediyl group;

X¹ and X² each independently represents —O—, —CO—O— or —O—CO—;

a represents 0 or 1; and

* represents a binding site to an oxygen atom.

<2> The compound according to <1>, wherein

W¹ is an adamantanediyl group or a cyclohexanediyl group.

<3> The compound according to <2>, wherein

the adamantanediyl group is any one of the groups represented byformulae (Ad-1) to (Ad-3);

wherein one of * is a binding site to A¹ and another * is a binding siteto a carbonyl group.

<4> The compound according to any one of <1> to <3>, wherein A¹ is asingle bond.

<5> The compound according to any one of <1> to <4>, wherein R² is a C₁to C₁₂ fluorinated alkyl group.

<6> The compound according to any one of <1> to <5>, wherein

R² is —(CH₂)_(n)—R^(f),

where n represents an integer of 1 to 6, and

R^(f) represents a C₁ to C₆ perfuloroalkyl group.

<7> The compound according to any one of <1> to <5>, wherein

R² is —CH(R^(fa))(R^(fb));

where R^(fa) and R^(fb) each independently represent a C₁ to C₆perfuloroalkyl group, provided that R^(fa) and R^(fb) have 11 or less ofcarbon atoms in total.

<8> A resin including a structural unit derived from the compoundaccording to any one of <1> to <7>.

<9> A resist composition including the resin according to <8>, a resinhaving an acid-labile group, and an acid generator.

<10> A method for producing a resist pattern including steps (1) to (5);

(1) applying the resist composition according to <9> onto a substrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

“(Meth)acrylic monomer” means a monomer having a structure of“CH₂═CH—CO—” or “CH₂═C(CH₃)—CO—”, as well as “(meth)acrylate” and“(meth)acrylic acid” mean “an acrylate or methacrylate” and “an acrylicacid or methacrylic acid,” respectively. Herein, chain structure groupsinclude those having a linear structure and those having a branchedstructure. The indefinite articles “a” and “an” are taken as the samemeaning as “one or more”.

In the specification, the term “solid components” means components otherthan solvents in a resist composition.

<Compound (I)>

The compound of the present invention (which is sometimes referred to as“compound (I)”) is a compound represented by the formula (I);

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom;

R² represents a C₁ to C₁₂ fluorinated saturated hydrocarbon group;

W¹ represents a C₅ to C₁₈ divalent alicyclic hydrocarbon group;

A¹ and A² each independently represent a single bond or*-A³-X¹-(A⁴-X²)_(a)—;

A³ and A⁴ each independently represent a C₁ to C₆ alkanediyl group;

X¹ and X² each independently represents —O—, —CO—O— or —O—CO—;

a represents 0 or 1; and

* represents a binding site to an oxygen atom.

Examples of the alkyl group of R¹ include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups,preferably include a C₁ to C₄ alkyl group, more preferably a methyl orethyl group.

Examples of the halogen atom for R¹ include fluorine, chlorine, bromineor iodine atom.

Examples of the alkyl group having the halogen atom for R¹ includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, perchloromethyl, perbromomethyl andperiodomethyl groups.

R¹ is preferably a hydrogen atom or a methyl group.

Examples of C₁ to C₁₂ fluorinated saturated hydrocarbon group of R²include difluoromethyl, trifluoromethyl, 1,1-difluoroethyl,2,2-difluoroethyl, 2,2,2-trifluoroethyl, perfluoroethyl,1,1,2,2-tetrafluoropropyl, 1,1,2,2,3,3-hexafluoropropyl, perfluoroethylmethyl, 1-(trifluoromethyl)-2,2,2-trifluoroethyl,1-(trifluoromethyl)-2,2,3,3,3-pentafluoropropyl,1-(perfluoroethyl)-2,2,3,3,3-pentafluoropropyl,1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl, perfluoropropyl,1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,2,3,3,4,4-octafluorobutyl, perfluorobutyl, 1,1-bis(trifluoromethyl)methyl-2,2,2-trifluoroethyl, 2-(perfluoropropyl)ethyl,1,1,2,2,3,3,4,4-octafluoropentyl s, perfluoropentyl,1,1,2,2,3,3,4,4,5,5-decafluoropentyl, 1,1-bis(trifluoromethyl)2,2,3,3,3-pentafluoropropyl, perfluoropentyl,2-(perfluorobutyl)ethyl, 1,1,2,2,3,3,4,4,5,5-decafluorohexyl,1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl, perfluoropentylmethyl,perfluorohexyl, perfluorocyclohexyl and perfluoroadamantyl groups.

R² is preferably a C₁ to C₁₂ fluorinated alkyl group, and morepreferably (CH₂)_(n)—R^(f) or —CH(R^(fa))(R^(fb)).

n represents an integer of 1 to 6, preferably 1 to 4, more preferably 1to 3, and still more preferably 1 or 2, further more preferably 2.

R^(f) represents a C₁ to C₆ perfuloroalkyl group, preferably a C₂ to C₄perfuloroalkyl group, and more preferably C₃ to C₄ perfuloroalkyl group.

R^(fa) and R^(fb) each independently represent a C₁ to C₆ perfuloroalkylgroup, preferably a C₁ to C₄ perfuloroalkyl group, more preferably C₁ toC₃ perfuloroalkyl group, and still more preferably a C₁ to C₂perfuloroalkyl group.

Examples of the C₅ to C₁₈ divalent alicyclic hydrocarbon group for W¹include cyclopentanediyl, cyclohexanediyl, adamantanediyl andnorbornanedily group. Among these, cyclohexanediyl and adamantanediylgroups are preferred, and an adamantanediyl group is more preferred.

The adamantanediyl group is preferably a group represented by any one ofthe formulae (Ad-1) to (Ad-3), more preferably a group represented byone of the formulae (Ad-1) to (Ad-2), and still more preferably a grouprepresented by the formula (Ad-1). In the formulaes (Ad-1) to (Ad-3),one of * is a bond to A¹ and another * is a bond to a carbonyl group.

Examples of the C₁ to C₆ alkanediyl group for A³ and A⁴ include a chainalkanediyl group such as methylene, ethylene, propane-1,3-diyl,butane-1,4-diyl, pentane-1,5-diyl and hexane-1,6-diyl groups; and

a branched alkanediyl group such as ethane-1,1-diyl, propane-1,2-diyl,butane-1,3-diyl, 2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,pentane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

A³ and A⁴ are preferably a C₁ to C₃ divalent alkanediyl group, and morepreferably a methylene group or an ethylene group.

Examples of *-A³-X¹-(A⁴-X²)_(a)— include *-A³-O—, *-A³-CO—O—,*-A³-O—CO—, *-A³-CO—O-A⁴-CO—O—, *-A³-O—CO-A⁴-O—, *-A³-O-A⁴-CO—O—,*-A³-CO—O-A⁴-O—CO— and *-A³-O—CO-A⁴-O—CO—. Among these, *-A³-O—,*-A³-CO—O—, *-A³-CO—O-A⁴-CO—O—, and *-A³-O-A⁴-CO—O— are preferredas*-A³-X¹-(A⁴-X²)_(a)—.

Each of A¹ and A² is preferably a single bond or *-A³-CO—O—, morepreferably a single bond, —CH₂—CO—O— or —C₂H₄—CO—O—, and still morepreferably a single bond or CH₂—CO—O—. Specifically, A¹ is preferably asingle bond. A² is preferably *-A³-CO—O—.

Examples of the compound (I) include the compounds represented by thefollowing ones.

Examples of the compound (I) also include the compounds of the formulae(I-1) to (I-24) in which a methyl group corresponding to R¹ has beenreplaced by a hydrogen atom.

<Method for Producing the Compound (I)>

A method for producing the compound (I) is described below.

The compound (I) can be obtained by reacting a compound represented bythe formula (I-a) with a compound represented by the formula (I-b) inpresence of a catalyst in a solvent.

Preferred examples of the solvent include chloroform, tetrahydrofuranand toluene.

Preferred examples of the catalyst include the basic catalyst such aspyridine and dimethylaminopyridine, and a known esterified catalyst suchas an acid catalyst and carbodiimide catalyst. The basic catalyst andthe known esterified catalyst can be used as a catalyst for thereaction.

Examples of the compound represented by the formula (I-a) include thesalt represented by the formula below which is available on the market.

Examples of the compound represented by the formula (I-b) include thesalts represented by the formulae below which are available on themarket.

Examples of the carbodiimide catalyst include the salt represented bythe formula below which is available on the market.

<Resin Containing a Structural Unit Derived From the Compound (I)>

The resin of the present invention is a resin having a structural unitderived from the compound (I) which structural unit is sometimesreferred to as “structural unit (I)”. The resin is sometimes referred toas “resin (X)”.

In the resin (X), the proportion of structural unit (I) is generally 10to 70% by mole, preferably 20 to 60% by mole, more preferably 30 to 50%by mole, with respect to the total structural units (100% by mole) ofthe resin (X).

In addition to the structural unit (I), the resin (X) may furtherincludes a structural unit having a fluorine atom (which structural unitis sometimes referred to as “structural unit (a4)”), a structural unithaving a non-leaving hydrocarbon group (which structural unit issometimes referred to as “structural unit (a5)”), a structural unithaving an acid-labile group (which structural unit is sometimes referredto as “structural unit (a1)”), a structural unit having no acid-labilegroup (which structural unit is sometimes referred to as “structuralunit (s)”) and a structural unit derived from another known monomer.Among these, the resin (X) preferably further includes the structuralunit (a4) and/or the structural unit (a5).

<Structural Unit (a4)>

The structural unit having a halogen atom preferably has a fluorineatom.

Examples of the structural unit (a4) include the structural unitsrepresented by the formula (a4-0).

wherein R⁵ represents a hydrogen atom or a methyl group,

L⁵ represent a single bond or a C₁ to C₄ saturated aliphatic hydrocarbongroup,

L³ represents a C₁ to C₈ perfluoroalkanediyl group or a C₅ to C₁₂perfluorocycloalkanediyl group, and

R⁶ represents a hydrogen atom or a fluorine atom.

Examples of the saturated aliphatic hydrocarbon group of L⁵ include aliner alkanediyl group such as methylene, ethylene, propane-1,3-diyl,butane-1,4-diyl; and a branched alkanediyl group such as a group inwhich a liner alkanediyl group has a side chain of an alkyl group (e.g.,methyl and ethyl groups), for example, ethane-1,1-diyl,propane-1,2-diyl, butane-1,3-diyl, 2-methylpropane-1,3-diyl and2-methylpropane-1,2-diyl groups.

Examples of the perfluoroalkanediyl group of L³ includedifluoromethylene, perfluoroethylene, perfluoroethyl fluoromethylene,perfluoropropane-1,3-diyl, a perfluoropropane-1,2-diyl,perfluoropropane-2,2-diyl, perfluorobutane-1,4-diyl,perfluorobutane-2,2-diyl, perfluorobutane-1,2-diyl,perfluoropentane-1,5-diyl, perfluoropentane-2,2-diyl,perfluoropentane-3,3-diyl, perfluorohexane-1,6-diyl,perfluorohexane-2,2-diyl, perfluorohexane-3,3-diyl,perfluoroheptane-1,7-diyl, perfluoroheptane-2,2-diyl,perfluoroheptane-3,4-diyl, perfluoroheptane-4,4-diyl,perfluorooctan-1,8-diyl, perfluorooctan-2,2-diyl,perfluorooctan-3,3-diyl and perfluorooctan-4,4-diyl groups.

Examples of the perfluoro cycloalkanediyl group of L³ includeperfluorocyclohexanediyl, perfluorocyclopentanediyl,perfluorocycloheptanediyl and perfluoroadamantanediyl groups.

L⁵ is preferably a single bond, methylene or ethylene group, and morepreferably a single bond or methylene group.

L³ is preferably a C₁ to C₆ perfluoroalkanediyl group, more preferably aC₁ to C₃ perfluoroalkanediyl group.

Examples of the structural unit (a4-0) include structural unitsrepresented by the formula (a4-0-1) to the formula (a4-0-32).

Examples of the structural unit (a4) include the structural unitsrepresented by the formula (a4-1):

wherein R^(a41) represents a hydrogen atom or a methyl group,

R^(a42) represents an optionally substituted C₁ to C₂₀ hydrocarbon groupwhere a methylene group may be replaced by an oxygen atom or a carbonylgroup, and

A^(a41) represents an optionally substituted C₁ to C₆ alkanediyl groupor a group represented by the formula (a-g1),

wherein s represents 0 or 1,

A^(a42) and A^(a44) independently represent an optionally substituted C₁to C₅ aliphatic hydrocarbon group,

A^(a43) represents a single bond or an optionally substituted C₁ to C₅aliphatic hydrocarbon group, and

X^(a41) and X^(a42) independently represent —O—, —CO—, —CO—O— or —O—CO—,

provided that the total carbon number contained in the group of A^(a42),A^(a43), A^(a44), X^(a41) and X^(a42) is 6 or less, and

at least one of A^(a41) and R^(a42) has a halogen atom as a substituent,and

* and ** represent a binding site, and * represents a binding site to—O—CO—R^(a42).

The hydrocarbon group of R^(a42) includes a chain and a cyclic aliphatichydrocarbon groups, an aromatic hydrocarbon group and a combinationthereof.

Examples of the chain aliphatic hydrocarbon group include an alkyl groupsuch as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, n-decyl, n-dodecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl andn-octadecyl groups. Examples of the cyclic aliphatic hydrocarbon groupinclude a monocyclic hydrocarbon group, i.e., cycloalkyl group such ascyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl groups; and polycyclichydrocarbon groups such as decahydronaphtyl, adamantyl and norbornylgroups as well as groups below. * represents a binding site.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, biphenyl, phenanthryl and fluorenyl groups.

The hydrocarbon group of R^(a42) is preferably a chain and a cyclicaliphatic hydrocarbon groups, and a combination thereof. The hydrocarbongroup may have a carbon-carbon unsaturated bond, is preferably a chainand a cyclic saturated aliphatic hydrocarbon groups, and a combinationthereof.

Examples of the substituent of R^(a42) include a fluorine atom or agroup represented by the formula (a-g3).

Examples of the halogen atom include fluorine, chlorine, bromine oriodine atom, and preferably a fluorine atom.*X^(a43)-A^(a45)  (a-g3)

wherein X^(a43) represent an oxygen atom, a carbonyl group, acarbonyloxy group or an oxycarbonyl group,

A^(a45) represents a C₁ to C₁₇ aliphatic hydrocarbon group that has ahalogen atom, and

* represents a binding site to carbonyl group.

Examples of the aliphatic hydrocarbon group of A^(a45) are the sameexamples as the group of R^(a42).

R^(a42) is preferably an aliphatic hydrocarbon group that may have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or an aliphatic hydrocarbon group having the group represented bythe formula (a-g3).

When R^(a42) is an aliphatic hydrocarbon group having a halogen atom, analiphatic hydrocarbon group having a fluorine atom is preferred, aperfluoroalkyl group or a perfulorocycloalkyl group are more preferred,a C₁ to C₆ perfluoroalkyl group is still more preferred, a C₁ to C₃perfluoroalkyl group is particularly preferred.

Examples of the perfluoroalkyl group include perfluoromethyl,perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl,perfluorohexyl, perfluoroheptyl and perfluorooctyl groups. Examples ofthe perfluorocycloalkyl group include perfluorocyclohexyl group.

When R^(a42) is an aliphatic hydrocarbon group having the grouprepresented by the formula (a-g3), the total carbon number contained inthe aliphatic hydrocarbon group including the group represented by theformula (a-g3) is preferably 15 or less, more preferably 12 or less. Thenumber of the group represented by the formula (a-g3) is preferably onewhen the group represented by the formula (a-g3) is the substituent.

The aliphatic hydrocarbon having the group represented by the formula(a-g3) is more preferably a group represented by the formula (a-g2);*-A^(a46)-X^(a44)-A^(a47)  (a-g2)

wherein A^(a46) represents a C₁ to C₁₇ aliphatic hydrocarbon group thatmay have a halogen atom,

X^(a44) represent a carbonyloxy group or an oxycarbonyl group,

A^(a47) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may havea halogen atom,

provided that the total carbon number contained in the group of A^(a46),X^(a44) and A^(a47) is 18 or less,

at least one of A^(a46) and A^(a47) has a halogen atom, and

* represents a binding site to carbonyl group.

The carbon number of the aliphatic hydrocarbon group of A^(a46) ispreferably 1 to 6, and more preferably 1 to 3.

The carbon number of the aliphatic hydrocarbon group of A^(a47) ispreferably 4 to 15, and more preferably 5 to 12, and cyclohexyl andadamantyl groups are still more preferred as the aliphatic hydrocarbongroup.

Preferred structure represented by the formula (a-g2),*-A^(a46)-X^(a44)-A^(a47) include the following ones.

Examples of the alkanediyl group of A^(a41) include a liner alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as propane-1,2-diyl, butan-1,3-diyl,2-methylpropane-1,2-diyl, 1-methylpropane-1,4-diyl,2-methylbutane-1,4-diyl groups.

Examples of the substituent of the alkanediyl group of A^(a41) include ahydroxy group and a C₁ to C₆ alkoxy group.

A^(a41) is preferably a C₁ to C₄ alkanediyl group, more preferably a C₂to C₄ alkanediyl group, and still more preferably ethylene group.

In the group represented by the formula (a-g1) (which is sometimesreferred to as “group (a-g1)”), examples of the aliphatic hydrocarbongroup of A^(a42), A^(a43) and A^(a44) include methylene, ethylene,propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,1-methylpropane-1,3-diyl, 2-methylpropane-1,3-diyl and2-methylpropane-1,2-diyl groups.

Examples of the substituent of the aliphatic hydrocarbon group ofA^(a42), A^(a43) and A^(a44) include a hydroxy group and a C₁ to C₆alkoxy group.

s is preferably 0.

Examples of the group (a-g1) in which X^(a42) represents an oxygen atominclude the following ones. In the formula, * and ** each represent abinding site, and ** represents a binding site to —O—CO—R^(a42).

Examples of the group (a-g1) in which X^(a42) represents a carbonylgroup include the following ones.

Examples of the group (a-g1) in which X^(a42) represents a carbonyloxygroup include the following ones.

Examples of the group (a-g1) in which X^(a42) represents an oxycarbonylgroup include the following ones.

The structural unit represented by the formula (a4-1) is preferablystructural units represented by the formula (a4-2) and the formula(a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group,

A^(f1) represent a C₁ to C₆ alkanediyl group, and

R^(f2) represents a C₁ to C₁₀ hydrocarbon group that has a fluorineatom.

Examples of the alkanediyl group of A^(f1) include a chain alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as 1-methylpropane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,1-methylbutane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

The hydrocarbon group of R^(f2) includes an aliphatic hydrocarbon groupand an aromatic hydrocarbon group. The aliphatic hydrocarbon groupincludes a chain and a cyclic groups, and a combination thereof. Thealiphatic hydrocarbon group is preferably an alkyl group and analicyclic hydrocarbon group.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and2-ethylhexyl groups.

Examples of the alicyclic hydrocarbon group include any of a monocyclicgroup and a polycyclic group. Examples of the monocyclic alicyclichydrocarbon group include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, andcyclodecyl groups. Examples of the polycyclic hydrocarbon groupsincludes decahydronaphthyl, adamantyl, 2-alkyladamantane-2-yl,1-(adamantane-1-yl) alkane-1-yl, norbornyl, methylnorbornyl andisobornyl groups.

Examples of the hydrocarbon group having a fluorine atom of R^(f2)include an alkyl group having a fluorine atom and an alicyclichydrocarbon group having a fluorine atom.

Specific examples of an alkyl group having a fluorine atom include afluorinated alkyl group such as difluoromethyl, trifluoromethyl,1,1-difluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl,perfluoroethyl, 1,1,2,2-tetrafluoropropyl, 1,1,2,2,3,3-hexafluoropropyl,perfluoroethylmethyl, 1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl,perfluoropropyl, 1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, perfluorobutyl,1,1-bis(trifluoromethyl)methyl-2,2,2-trifluoroethyl,2-(perfluoropropyl)ethyl, 1,1,2,2,3,3,4,4-octafluoropentyl,perfluoropentyl, 1,1,2,2,3,3,4,4,5,5-decafluoro pentyl,1,1-bis(trifluoromethyl)2,2,3,3,3-pentafluoropropyl, perfluoropentyl,2-(perfluorobutyl)ethyl, 1,1,2,2,3,3,4,4,5,5-decafluorohexyl,1,1,2,2,3,3,4,4,5,5,6,6-dodeca fluorohexyl, perfluoropentylmethyl andperfluorohexyl groups.

Examples of the alicyclic hydrocarbon group having a fluorine atominclude a fluorinated cycloalkyl group such as perfluorocyclohexyl andperfluoroadamantyl groups.

In the formula (a4-2), A^(f1) is preferably a C₂ to C₄ alkanediyl group,and more preferably ethylene group.

R^(f2) is preferably a C₁ to C₆ fluorinated alkyl group:

wherein R^(f11) represents a hydrogen atom or a methyl group,

A^(f11) represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ aliphatic hydrocarbon group that may hasa fluorine atom,

X^(f12) represents an oxycarbonyl group or a carbonyloxy group,

A^(f14) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may hasa fluorine atom, and

provided that at least one of A^(f13) and A^(f14) represents analiphatic hydrocarbon group having a fluorine atom.

Examples of the alkanediyl group of A^(f11) are the same examples as thealkanediyl group of A^(f1).

Examples of the aliphatic hydrocarbon group of A^(f13) include any of adivalent chain or cyclic hydrocarbon group, or a combination thereof.The aliphatic hydrocarbon group may have a carbon-carbon unsaturatedbond, and is preferably a saturated aliphatic hydrocarbon group.

The aliphatic hydrocarbon group that may has a fluorine atom of A^(f13)is the saturated aliphatic hydrocarbon group that may has a fluorineatom, and preferably a perfuloroalkandiyl group.

Examples of the divalent chain aliphatic hydrocarbon that may have afluorine atom include an alkanediyl group such as methylene, ethylene,propanediyl, butanediyl and pentanediyl groups; a perfluoroalkanediylgroup such as difluoromethylene, perfluoroethylene,perfluoropropanediyl, perfluorobutanediyl and perfluoropentanediylgroups.

The divalent cyclic aliphatic hydrocarbon group that may have a fluorineatom is any of monocyclic or polycyclic group.

Examples monocyclic aliphatic hydrocarbon group include cyclohexanediyland perfluorocyclohexanediyl groups.

Examples polycyclic aliphatic hydrocarbon group include adamantanediyl,norbornanediyl, and perfluoroadamantanediyl groups.

Examples of the aliphatic hydrocarbon group of A^(f14) include any of achain or a cyclic hydrocarbon group, or a combination thereof. Thealiphatic hydrocarbon group may have a carbon-carbon unsaturated bond,and is preferably a saturated aliphatic hydrocarbon group.

The aliphatic hydrocarbon group that may has a fluorine atom of A^(f14)is preferably the saturated aliphatic hydrocarbon group that may have afluorine atom.

Examples of the chain aliphatic hydrocarbon group that may have ahalogen atom include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, pentyl, hexyl, perfluorohexyl,hepthyl, perfluoroheptyl, octyl and perfluorooctyl groups.

The cyclic aliphatic hydrocarbon group that may have a halogen atom isany of monocyclic or polycyclic group. Examples of the group containingthe monocyclic aliphatic hydrocarbon group includes cyclopropylmethyl,cyclopropyl, cyclobutylmethyl, cyclopentyl, cyclohexyl andperfluorocyclohexyl groups. Examples of the group containing thepolycyclic aliphatic hydrocarbon group includes adamantyl,adamantylmethyl, norbomyl, norbornylmethyl, perfluoroadamantyl andperfluoroadamantylmethyl groups

In the formula (a4-3), A^(f11) is preferably ethylene group.

The aliphatic hydrocarbon group of A^(f13) is preferably a C₁ to C₆aliphatic hydrocarbon group, more preferably a C₂ to C₃ aliphatichydrocarbon group.

The aliphatic hydrocarbon group of A^(f14) is preferably a C₃ to C₁₂aliphatic hydrocarbon group, more preferably a C₃ to C₁₀ aliphatichydrocarbon group. Among these, A^(f14) is preferably a group containinga C₃ to C₁₂ alicyclic hydrocarbon group, more preferablycyclopropylmethyl, cyclopentyl, cyclohexyl, norbornyl and adamantylgroup.

Examples of the structural unit (a4-2) include structural unitsrepresented by the formula (a4-1-1) to the formula (a4-1-22).

Examples of the structural unit (a4-3) include structural unitspresented by the formula (a4-1′-1) to the formula (A4-1′-22).

Examples of the structural unit (a4) include a structural unit presentedby the formula (a4-4):

wherein R^(f21) represents a hydrogen atom or a methyl group,

A^(f21) represents —(CH₂)_(j1)—, —(CH₂)_(j2)—O—(CH₂)_(j3)— or—(CH₂)_(j4)—CO—O—(CH₂)_(j5)—,

j1 to j5 independently represents an integer of 1 to 6, and

R^(f22) represents a C₁ to C₁₀ hydrocarbon group having a fluorine atom.

Examples of the hydrocarbon group having a fluorine atom of R^(f22) arethe same examples as the hydrocarbon group described in R^(f2) in theformula (a4-2). R^(f22) is preferably a C₁ to C₁₀ alkyl having afluorine atom or a C₃ to C₁₀ alicyclic hydrocarbon group having afluorine atom, more preferably a C₁ to C₁₀ alkyl having a fluorine atom,and still more preferably a C₁ to C₆ alkyl having a fluorine atom.

In the formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, morepreferably methylene or ethylene group, and still more preferablymethylene group.

Examples of the structural unit represented by the formula (a4-4)include the following ones.

When the resin (X) contains the structural unit (a4), the proportionthereof is generally 1 to 20% by mole, preferably 2 to 15% by mole, morepreferably 3 to 10% by mole, with respect to the total structural units(100% by mole) of the resin (X).

<Structural Unit (a5)>

Examples of the non-leaving hydrocarbon group in the structural unit(a5) include a chain, a branched or a cyclic hydrocarbon group. Amongthese, the structural unit (a5) is preferably a structural unitcontaining an alicyclic hydrocarbon group.

The structural unit (a5) is, for example, a structural unit representedby the formula (a5-1):

wherein R⁵¹ represents a hydrogen atom or a methyl group,

R⁵² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogenatom may be replaced by a C₁ to C₈ aliphatic hydrocarbon group or ahydroxy group, provided that a hydrogen atom contained in the carbonatom bonded to L⁵¹ is not replaced by the C₁ to C₈ aliphatic hydrocarbongroup, and

L⁵¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group.

Examples of the alicyclic hydrocarbon group of R⁵² include any one of amonocyclic group or a polycyclic group. Examples of the monocyclicalicyclic hydrocarbon group include cyclopropyl, cyclobutyl, cyclopentyland cyclohexyl groups. Examples of the polycyclic hydrocarbon groupinclude adamantyl and norbornyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group include an alkylgroup such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octylgroups.

Examples of the alicyclic hydrocarbon group having a substituent include3-hydroxyadamantyl and 3-methyladamantyl.

R⁵² is preferably an unsubstituted C₃ to C₁₈ alicyclic hydrocarbongroup, and more preferably adamantyl, norbornyl and cyclohexyl groups.

Examples of the divalent saturated hydrocarbon group of L⁵¹ include adivalent aliphatic saturated hydrocarbon group and a divalent alicyclicsaturated hydrocarbon group, and a divalent aliphatic saturatedhydrocarbon group is preferred.

Examples of the divalent aliphatic saturated hydrocarbon group includean alkanediyl such as methylene, ethylene, propanediyl, butanediyl andpentanediyl.

Examples of the divalent alicyclic saturated hydrocarbon group includeany of a monocyclic group and a polycyclic group. Examples of themonocyclic alicyclic saturated hydrocarbon groups includecycloalkanediyl such as cyclopentanediyl and cyclohexanediyl groups.Examples of the polycyclic saturated hydrocarbon groups includeadamantanediyl and norbornanediyl groups.

Examples of the group in which a methylene group contained in thesaturated hydrocarbon group is replaced by an oxygen atom or a carbonylgroup include groups represented by the formula (L1-1) to the formula(L1-4). In the formula (L1-1) to the formula (L1-4), * represents abinding site to an oxygen atom.

wherein X^(X1) represents an oxycarbonyl group or a carbonyloxy group,

L^(X1) represents a C₁ to C₁₆ divalent saturated aliphatic hydrocarbongroup,

L^(X2) represents a single bond or a C₁ to C₁₅ divalent saturatedhydrocarbon group,

provided that the total carbon number contained in the group of L^(X1)and L^(X2) is 16 or less;

L^(X3) represents a single bond or a C₁ to C₁₇ divalent saturatedaliphatic hydrocarbon group,

L^(X4) represents a single bond or a C₁ to C₁₆ divalent saturatedhydrocarbon group,

provided that the total carbon number contained in the group of L^(X3)and L^(X4) is 17 or less;

L^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L^(X6) and L^(X7) independently represents a single bond or a C₁ to C₁₄divalent saturated hydrocarbon group,

provided that the total carbon number contained in the group of L^(X5),L^(X6) and L^(X7) is 15 or less;

L^(X8) and L^(X9) independently represents a single bond or a C₁ to C₁₂divalent saturated hydrocarbon group,

W^(X1) represents a C₃ to C₁₅ divalent saturated alicyclic hydrocarbongroup,

provided that the total carbon number contained in the group of L^(X8),L^(X9) and W^(X1) is 15 or less.

L^(X1) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably methylene or ethylene group.

L^(X2) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond.

L^(X3) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup.

L^(X4) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X5) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably methylene or ethylene group.

L^(X6) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably methylene or ethylenegroup.

L^(X7) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X8) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond ormethylene group.

L^(X9) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond ormethylene group.

W^(X1) is preferably a C₃ to C₁₀ divalent saturated alicyclichydrocarbon group, and more preferably cyclohexanediyl or adamantanediylgroup.

Examples of the group represented by the formula (L1-1) include thefollowing ones.

Examples of the group represented by the formula (L1-2) include thefollowing ones.

Examples of the group represented by the formula (L1-3) include thefollowing ones.

Examples of the group represented by the formula (L1-4) include thefollowing ones.

L⁵¹ is preferably a single bond, methylene group, ethylene group or thegroups represented by the formula (L1-1), and more preferably a singlebond or the groups represented by the formula (L1-1).

Examples of the structural unit (a5-1) include the following ones.

When the resin (X) contains the structural unit (a5), the proportionthereof is generally 1 to 70% by mole, preferably 2 to 60% by mole, morepreferably 3 to 50% by mole, with respect to the total structural units(100% by mole) of the resin (X).

The resin (X) may further includes a structural unit other thanstructural units described above. Examples of the structural unitinclude a known structural unit.

The weight average molecular weight of the resin (X) is preferably 6,000or more (more preferably 7,000 or more), and 80,000 or less (morepreferably 60,000 or less). In this specification, the weight averagemolecular weight is a value determined by gel permeation chromatography.

<Resist Composition>

The resist composition of the present invention contains the resin (X),a resin having an acid-labile group and an acid generator (which issometimes referred to as “acid generator (B)”). Here the “acid-labilegroup” means a group having a leaving group which is detached bycontacting with an acid resulting in forming a hydrophilic group such asa hydroxy or carboxy group.

The resist composition preferably contains a quencher (which issometimes referred to as “quencher (C)”) or a solvent (which issometimes referred to as “solvent (E)”), more preferably contain thequencher (C) and the solvent (E). The resist composition of the presentinvention preferably contains a salt weaker in acidity such as a weakacid inner salt (which is sometimes referred to as “weak acid inner salt(D)”) as the quencher (C).

<Resin (A)>

The resin includes a structural unit having an acid-labile group (whichis sometimes referred to as “structural unit (a1)”). The resin issometimes referred to as “resin (A)”.

The resin (A) may preferably include a structural unit other than thestructural unit (a1). Examples of the structural unit other than thestructural unit (a1) include a structural unit not having an acid-labilegroup (which is sometimes referred to as “structural unit (s1)”), and aknown structural unit.

<Structural Unit (a1)>

The structural units (a1) is derived from a monomer (which is sometimesreferred to as “monomer (a1)”) having an acid-labile group.

In the resin (A), the acid-labile group contained in the structural unit(a1) is preferably the following group (1) and/or the group (2):

wherein R^(a1) to R^(a3) independently represent a C₁ to C₈ alkyl group,a C₃ to C₂₀ alicyclic hydrocarbon group or combination thereof, orR^(a1) and R^(a2) may be bonded together with a carbon atom bondedthereto to form a C₃ to C₂₀ divalent alicyclic hydrocarbon group;

na represents an integer of 0 or 1;

* represents a binding site.

wherein R^(a1′) and R^(a2′) independently represent a hydrogen atom or aC₁ to C₁₂ hydrocarbon group, R^(a3′) represents a C₁ to C₂₀ hydrocarbongroup, or R^(a2′) and R^(a3′) may be bonded together with a carbon atomand X bonded thereto to form a divalent C₃ to C₂₀ heterocyclic group,and a methylene group contained in the hydrocarbon group or the divalentheterocyclic group may be replaced by an oxygen atom or sulfur atom;

X represents —O— or —S—;

* represents a binding site.

Examples of the alkyl group of R^(a1) to R^(a3) include methyl, ethyl,propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a1) to R^(a3) includemonocyclic groups such as a cycloalkyl group, i.e., cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl groups; and polycyclic hydrocarbongroups such as decahydronaphtyl, adamantyl and norbornyl groups as wellas groups below. * represents a binding site.

The alicyclic hydrocarbon group of R^(a1) to R^(a3) preferably has 3 to16 carbon atoms.

Examples of groups combining the alkyl group and the alicyclichydrocarbon group include methyl cyclohexyl, dimethyl cyclohexyl, methylnorbornyl and cyclohexylmethyl, adamantylmethyl and norbornyletylgroups.

na is preferably an integer of 0.

When R^(a1) and R^(a2) is bonded together to form a divalent alicyclichydrocarbon group, examples of the group-C(R^(a1))(R^(a2))(R^(a3))include groups below. The divalent alicyclic hydrocarbon grouppreferably has 3 to 12 carbon atoms. * represent a binding site to —O—.

Specific examples of the group represented by the formula (1) include,for example,

1,1-dialkylalkoxycarbonyl group (a group in which R^(a1) to R^(a3) arealkyl groups, preferably tert-butoxycarbonyl group, in the formula (1)),

2-alkyladamantane-2-yloxycarbonyl group (a group in which R^(a1), R^(a2)and a carbon atom form adamantyl group, and R^(a3) is alkyl group, inthe formula (1)), and

1-(adamantane-1-yl)-1-alkylalkoxycarbonyl group (a group in which R^(a1)and R^(a2) are alkyl group, and R^(a3) is adamantyl group, in theformula (1)).

The hydrocarbon group of R^(a1′) to R^(a3′) includes any of an alkylgroup, an alicyclic hydrocarbon group, an aromatic hydrocarbon group anda group formed by combining them.

Examples of the alkyl group and the alicyclic hydrocarbon group are thesame examples as described above.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the divalent heterocyclic group formed by bonding withR^(a2′) and R^(a3′) include groups below.

At least one of R^(a1′) and R^(a2′) is preferably a hydrogen atom.

Specific examples of the group represented by the formula (2) include agroup below. * represents a binding site.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylene unsaturated bond, and more preferably a (meth)acrylicmonomer having the acid-labile group.

Among the (meth)acrylic monomer having an acid-labile group, a monomerhaving a C₅ to C₂₀ alicyclic hydrocarbon group is preferred. When aresin (A) having a structural unit derived from a monomer (a1) having abulky structure such as the alicyclic hydrocarbon group is used for aresist composition, the resist composition having excellent resolutiontends to be obtained.

Examples of a structural unit derived from the (meth)acrylic monomerhaving the group represented by the formula (1) preferably includestructural units represented by the formula (a1-0), the formula (a1-1)and the formula (a1-2) below. These may be used as a single structuralunit or as a combination of two or more structural units. The structuralunit represented by the formula (a1-0), the structural unit representedby the formula (a1-1) and a structural unit represented by the formula(a1-2) are sometimes referred to as “structural unit (a1-0)”,“structural unit (a1-1)” and “structural unit (a1-2)”), respectively,and monomers deriving the structural unit (a1-0), the structural unit(a1-1) and the structural unit (a1-2) are sometimes referred to as“monomer (a1-0)”, “monomer (a1-1)” and “monomer (a1-2)”), respectively:

wherein L^(a01) represents —O— or *—O—(CH₂)_(k01)—CO—O—,

k01 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a01) represents a hydrogen atom or a methyl group, and

R^(a02), R^(a03) and R^(a04) independently represent a C₁ to C₈ alkylgroup, a C₃ to C₁₈ alicyclic hydrocarbon group or combination thereof.

L^(a01) is preferably an —O— or *—O—(CH₂)_(k01)—CO—O— in which k01 ispreferably an integer of 1 to 4, more preferably an integer of 1, morepreferably an —O—.

Examples of the alkyl group and an alicyclic hydrocarbon group ofR^(a02), R^(a03) and R^(a04) and combination thereof are the sameexamples as the group described in R^(a1) to R^(a3) in the formula (1).

The alkyl group of R^(a02), R^(a03) and R^(a04) is preferably a C₁ to C₆alkyl group.

The alicyclic hydrocarbon group of R^(a02), R^(a03) and R^(a04) ispreferably a C₃ to C₈ alicyclic hydrocarbon group, more preferably a C₃to C₆ alicyclic hydrocarbon group.

The group formed by combining the alkyl group and the alicyclichydrocarbon group has preferably 18 or less of carbon atom. Examples ofthose groups include methyl cyclohexyl, dimethyl cyclohexyl and methylnorbornyl groups.

R^(a02) and R^(a03) is preferably a C₁ to C₆ alkyl group, morepreferably a methyl or ethyl group.

R^(a04) is preferably a C₁ to C₆ alkyl group or C₅ to C₁₂ alicyclichydrocarbon group, more preferably a methyl, ethyl, cyclohexyl oradamantyl group.

wherein L^(a1) and L^(a2) independently represent —O— or*—O—(CH₂)_(k1)—CO—O—,

k1 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a4) and R^(a5) independently represent a hydrogen atom or a methylgroup,

R^(a6) and R^(a7) independently represent a C₁ to C₈ alkyl group, a C₃to C₁₈ alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

L^(a1) and L^(a2) are preferably —O— or *—O—(CH₂)_(k1′)—CO—O— in whichk1′ represents an integer of 1 to 4 and more preferably 1, still morepreferably —O—.

R^(a4) and R^(a5) are preferably a methyl group.

Examples of the alkyl group of R^(a6) and R^(a7) include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a6) and R^(a7) includemonocyclic hydrocarbon groups such as a cycloalkyl group, i.e.,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl and cyclooctyl groups; and polycyclichydrocarbon groups such as decahydronaphtyl, adamantyl,2-alkyadamantane-2-yl, 1-(adamantane-1-yl) alkane-1-yl, norbornyl,methyl norbornyl and isobornyl groups.

Examples of group formed by combining the alkyl group and the alicyclichydrocarbon group of R^(a6) and R^(a7) include an aralkyl group such asbenzyl and phenethyl groups.

The alkyl group of R^(a6) and R^(a7) is preferably a C₁ to C₆ alkylgroup.

The alicyclic hydrocarbon group of R^(a6) and R^(a7) is preferably a C₃to C₈ alicyclic hydrocarbon group, more preferably a C₃ to C₆ alicyclichydrocarbon group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1, and more preferably 1.

Examples of the monomer (a1-0) preferably include monomers representedby the formula (a1-0-1) to the formula (a1-0-12), and more preferablymonomers represented by the formula (a1-0-1) to the formula (a1-0-10)below.

Examples of the structural units (a1-0) include structural units inwhich a methyl group corresponding to R^(a01) in the structural unitsrepresented as above has been replaced by a hydrogen atom.

Examples of the monomer (a1-1) include monomers described in JP2010-204646A. Among these, the monomers are preferably monomersrepresented by the formula (a1-1-1) to the formula (a1-1-8), and morepreferably monomers represented by the formula (a1-1-1) to the formula(a1-1-4) below.

Examples of the monomer (a1-2) include 1-methylcyclopentane-1-yl(meth)acrylate, 1-ethylcyclopentane-1-yl (meth)acrylate,1-methylcyclohexane-1-yl (meth)acrylate, 1-ethylcyclohexane-1-yl(meth)acrylate, 1-ethylcycloheptane-1-yl (meth)acrylate,1-ethylcyclooctane-1-yl (meth)acrylate, 1-isopropylcyclopentane-1-yl(meth)acrylate and 1-isopropylcyclohexane-1-yl (meth)acrylate. Amongthese, the monomers are preferably monomers represented by the formula(a1-2-1) to the formula (a1-2-12), and more preferably monomersrepresented by the formula (a1-2-3), the formula (a1-2-4), the formula(a1-2-9) and the formula (a1-2-10), and still more preferably monomerrepresented by the formula (a1-2-3) and the formula (a1-2-9) below.

When the resin (A) contains the structural unit (a1-0) and/or thestructural unit (a1-1) and/or the structural unit (a1-2), the totalproportion thereof is generally 10 to 95% by mole, preferably 15 to 90%by mole, more preferably 20 to 85% by mole, with respect to the totalstructural units (100% by mole) of the resin (A).

Further, examples of the structural unit (a1) having a group (1) includea structural unit presented by the formula (a1-3). The structural unitrepresented by the formula (a1-3) is sometimes referred to as“structural unit (a1-3)”. The monomer from which the structural unit(a1-3) is derived is sometimes referred to as “monomer (a1-3)”.

wherein R^(a9) represents a carboxy group, a cyano group, a —COOR^(a13),a hydrogen atom or a C₁ to C₃ aliphatic hydrocarbon group that may havea hydroxy group,

R^(a13) represents a C₁ to C₈ aliphatic hydrocarbon group, a C₃ to C₂₀alicyclic hydrocarbon group or a group formed by combining thereof, ahydrogen atom contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by a hydroxy group, a amethylene group contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by an oxygen atom or acarbonyl group, and

R^(a10), R^(a11) and R^(a12) independently represent a C₁ to C₈ alkylhydrocarbon group, a C₃ to C₂₀ alicyclic hydrocarbon group or a groupformed by combining them, or R^(a10) and R^(a11) may be bonded togetherwith a carbon atom bonded thereto to form a C₁ to C₂₀ divalenthydrocarbon group.

Here, examples of —COOR^(a13) group include a group in which a carbonylgroup is bonds to the alkoxy group, such as methoxycarbonyl andethoxycarbonyl groups.

Examples of the aliphatic hydrocarbon group that may have a hydroxygroup of R^(a9) include methyl, ethyl, propyl, hydroxymethy and2-hydroxyethyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group of R^(a13) includemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the C₃ to C₂₀ alicyclic hydrocarbon group of R^(a13) includecyclopentyl, cyclopropyl, adamantyl, adamantylmetyl,1-(adamantyl-1-yl)-methylethyl, 2-oxo-oxolane-3-yl, 2-oxo-oxolane-4-ylgroups.

Examples of the alkyl group of R^(a10) to R^(a12) include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a10) to R^(a12)include monocyclic hydrocarbon groups such as a cycloalkyl group, i.e.,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl groups; andpolycyclic hydrocarbon groups such as decahydronaphtyl, adamantyl,2-alkyl-2-adamantyl, 1-(adamantane-1-yl) alkane-1-yl, norbornyl, methylnorbornyl and isobornyl groups.

When R^(a10) and R^(a11) is bonded together with a carbon atom bondedthereto to form a divalent hydrocarbon group, examples of thegroup-C(R^(a10))(R^(a11))(R^(a12)) include groups below.

Examples of the monomer (a1-3) include tert-butyl5-norbornene-2-carboxylate, 1-cyclohexyl-1-methylethyl5-norbornene-2-carboxylate, 1-methylcyclohexyl5-norbornene-2-carboxylate, 2-methy-2-adamantane-2-yl5-norbornene-2-carboxylate, 2-ethyl-2-adamantane-2-yl5-norbornene-2-carboxylate, 1-(4-methycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-(4-hydroxycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-methyl-(4-oxocyclohexyl)-1-ethyl5-norbornene-2-carboxylate, and 1-(1-adamantane-1-yl)-1-methylethyl5-norbornene-2-carboxylate.

The resin (A) having a structural unit (a1-3) can improve the resolutionof the obtained resist composition because it has a bulky structure, andalso can improve a dry-etching tolerance of the obtained resistcomposition because of incorporated a rigid norbornene ring into a mainchain of the resin (A).

When the resin (A) contains the structural unit (a1-3), the proportionthereof is generally 10% by mole to 95% by mole, preferably 15% by moleto 90% by mole, and more preferably 20% by mole to 85% by mole, withrespect to the total structural units constituting the resin (A) (100%by mole).

Examples of a structural unit (a1) having a group (2) include astructural unit represented by the formula (a1-4). The structural unitis sometimes referred to as “structural unit (a1-4)”.

-   wherein R^(a32) represents a hydrogen atom, a halogen atom or a C₁    to C₆ alkyl group that may have a halogen atom,-   R^(a33) in each occurrence independently represent a halogen atom, a    hydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂    to C₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group or    methacryloyloxy group,-   1a represents an integer 0 to 4,-   R^(a34) and R^(a35) independently represent a hydrogen atom or a C₁    to C₁₂ hydrocarbon group; and-   R^(a36) represents a C₁ to C₂₀ hydrocarbon group, or R^(a35) and    R^(a36) may be bonded together with a C—O bonded thereto to form a    divalent C₂ to C₂₀ hydrocarbon group, and a methylene group    contained in the hydrocarbon group or the divalent hydrocarbon group    may be replaced by an oxygen atom or sulfur atom.

Examples of the alkyl group of R^(a32) and R^(a33) include methyl,ethyl, propyl, isopropyl, butyl, pentyl and hexyl groups. The alkylgroup is preferably a C₁ to C₄ alkyl group, and more preferably a methylor ethyl group, and still more preferably a methyl group.

Examples of the halogen atom of R^(a32) and R^(a33)include fluorine,chlorine, bromine or iodine atom.

Examples of the alkyl group that may have a halogen atom includetrifluoromethyl, difluoromethyl, methyl, perfluoromethyl,1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl,1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

Examples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, and hexyloxy groups. The alkoxy group is preferably a C₁ toC₄ alkoxy group, more preferably a methoxy and ethoxy group, and stillmore preferably methoxy group.

Examples of the acyl group include acetyl, propanonyl and butylylgroups.

Examples of the acyloxy group include acetyloxy, propanonyloxy andbutylyloxy groups.

Examples of the hydrocarbon group of R^(a34) and R^(a35) are the sameexamples as described in R^(a1′) to R^(a2′) in the formula (2).

Examples of hydrocarbon group of R^(a36) include a C₁ to C₁₈ alkylgroup, a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a group formed by combining them.

In the formula (a1-4), R^(a32) is preferably a hydrogen atom.

R^(a33) is preferably a C₁ to C₄ alkoxy group, more preferably a methoxyand ethoxy groups, and still more preferably methoxy group.

1a is preferably 0 or 1, and more preferably 0.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a C₁ to C₁₂ hydrocarbon group, and more preferablya methyl or ethyl group.

The hydrocarbon group of R^(a36) is preferably a C₁ to C₁₈ alkyl group,a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a combination thereof, and more preferably a C₁ toC₁₈ alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a C₇ to C₁₈aralkyl group. The alkyl group and the alicyclic hydrocarbon group ofR^(a36) is preferably not substituted. When the aromatic hydrocarbongroup of R^(a36) has a substituent, the substituent is preferably a C₆to C₁₀ aryloxy group.

Examples of the monomer from which a structural unit (a1-4) is derivedinclude monomers described in JP 2010-204646A. Among these, the monomersare preferably monomers represented by the formula (a1-4-1) to theformula (a1-4-7), and more preferably monomers represented by theformula (a1-4-1) to the formula (a1-4-5) below.

When the resin (A) contains the structural unit (a1-4), the proportionthereof is generally 10% by mole to 95% by mole, preferably 15% by moleto 90% by mole, more preferably 20% by mole to 85% by mole, with respectto the total structural units constituting the resin (A) (100% by mole).

Examples of a structural unit having an acid-labile group include astructural unit represented by the formula (a1-5). Such structural unitis sometimes referred to as “structural unit (a1-5)”.

wherein R^(a8) represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom,

Z^(a1) represent a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-,

h3 represents an integer of 1 to 4,

* represents a binding site to L⁵¹,

L⁵¹, L⁵² and L⁵³ independently represent —O— or —S—,

s1 represents an integer of 1 to 3, and

s1′ represents an integer of 0 to 3.

In the formula (a1-5), R^(a8) is preferably a hydrogen atom, a methylgroup or trifluoromethyl group;

L⁵¹ is preferably —O—;

L⁵² and L⁵³ are independently preferably —O— or —S—, and more preferablyone is —O— and another is —S—.

s1 is preferably 1;

s1′ is preferably an integer of 0 to 2;

Z^(a1) is preferably a single bond or *—CH₂—CO—O—.

Examples of a monomer from which a structural unit (a1-5) is derivedinclude a monomer described in JP 2010-61117A. Among these, the monomersare preferably monomers represented by the formula (a1-5-1) to theformula (a1-5-4), and more preferably monomers represented by theformula (a1-5-1) to the formula (a1-5-2) below.

When the resin (A) contains the structural unit (a1-5), the proportionthereof is generally 1% by mole to 50% by mole, preferably 3% by mole to45% by mole, and more preferably 5% by mole to 40% by mole, with respectto the total structural units (100% by mole) constituting the resin (A).

Examples of a structural unit (a1) having an acid-labile group in aresin (A) is preferably at least one, more preferably two or morestructural units selected from the structural unit (a1-0), thestructural unit (a1-1), the structural unit (a1-2), the structural unit(a1-5), still more preferably a combination of the structural unit(a1-1) and the structural unit (a1-2), a combination of the structuralunit (a1-1) and the structural unit (a1-5), a combination of thestructural unit (a1-1) and the structural unit (a1-0), a combination ofthe structural unit (a1-2) and the structural unit (a1-0), a combinationof the structural unit (a1-5) and the structural unit (a1-0), acombination of the structural unit (a1-0), the structural unit (a1-1)and the structural unit (a1-2), a combination of the structural unit(a1-0), the structural unit (a1-1) and the structural unit (a1-5), inparticular preferably a combination of the structural unit (a1-1) andthe structural unit (a1-2), and a combination of the structural unit(a1-1) and the structural unit (a1-5).

<Structural Unit Having No Acid-Labile Group (s)>

The structural units (s) is derived from a monomer (which is sometimesreferred to as “monomer (s)”) having no acid-labile group.

For the monomer (s) from which a structural unit (s) is derived, a knownmonomer having no acid-labile group can be used.

As the structural unit (s), a structural unit having a hydroxy group ora lactone ring but having no acid-labile group is preferred. When aresin containing the structural unit derived from a structural unithaving hydroxy group but having no acid-labile group (such structuralunit is sometimes referred to as “structural unit (a2)”) and/or astructural unit having a lactone ring but having no acid-labile group(such structural unit is sometimes referred to as “structural unit(a3)”) is used, the adhesiveness of resist to a substrate and resolutionof resist pattern tend to be improved.

<Structural Unit (a2)>

The structural unit (a2) having a hydroxy group may be an alcoholichydroxy group or a phenolic hydroxy group.

When KrF excimer laser lithography (248 nm), or high-energy irradiationsuch as electron beam or EUV (extreme ultraviolet) is used for theresist composition, using the structural unit having a phenolic hydroxygroup as structural unit (a2) is preferred.

When ArF excimer laser lithography (193 nm) is used, using thestructural unit having an alcoholic hydroxy group as the structural unit(a2) is preferred, using the structural represented by the formula(a2-1) is more preferred.

The structural unit (a2) may be used as a single structural unit or as acombination of two or more structural units.

Examples of the structural unit (a2) having a phenolic hydroxy groupinclude a structural unit (which is sometimes referred to as “structuralunit (a2-0)”) represented by the formula (a2-0).

-   wherein R^(a30) represents a hydrogen atom, a halogen atom or a C₁    to C₆ alkyl group that may have a halogen atom,-   R^(a31) in each occurrence independently represents a halogen atom,    a hydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a    C₂ to C₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group    or methacryloyloxy group, and-   ma represents an integer 0 to 4.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl,butyl, n-pentyl and n-hexyl groups.

Example of the halogen atom is a chlorine atom, a fluorine atom andbromine atom.

Examples of a C₁ to C₆ alkyl group that may have a halogen atom ofR^(a30) include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

R^(a30) is preferably a hydrogen atom or a C₁ to C₄ alkyl group, andmore preferably a hydrogen atom, methyl or ethyl group, and still morepreferably a hydrogen atom or methyl group.

Examples of a C₁ to C₆ alkoxy group of R^(a31) include methoxy, ethoxy,propoxy, butoxy, pentyloxy, and hexyloxy groups. R^(a31) is preferably aC₁ to C₄ alkoxy group, more preferably a methoxy and ethoxy group, andstill more preferably methoxy group.

Examples of the acyl group include acetyl, propanonyl and butylylgroups.

Examples of the acyloxy group include acetyloxy, propanonyloxy andbutylyloxy groups.

ma is preferably 0, 1 or 2, more preferably 0 or 1, still morepreferably 0.

The structural unit (a2-0) having a phenolic hydroxy group is preferablya structural unit represented below.

Among these, a structural unit represented by the formula (a2-0-1) orthe formula (a2-0-2) is preferred.

Examples of a monomer from which the structural unit (a2-0) is derivedinclude monomers described in JP2010-204634A.

The resin (A) which contains the structural units (a2) having a phenolichydroxy group can be produced, for example, by polymerizing a monomerwhere its phenolic hydroxy group has been protected with a suitableprotecting group, followed by deprotection. The deprotection is carriedin such a manner that an acid-labile group in the structural unit (a1)is significantly impaired. Examples of the protecting group for aphenolic hydroxy group include an acetyl group.

When the resin (A) contains the structural unit (a2-0) having thephenolic hydroxy group, the proportion thereof is generally 5% by moleto 95% by mole, preferably 10% by mole to 80% by mole, more preferably15% by mole to 80% by mole, with respect to the total structural units(100% by mole) constituting the resin (A).

Examples of the structural unit (a2) having alcoholic hydroxy groupinclude the structural unit (which is sometimes referred to as“structural unit (a2-1)”) represented by the formula (a2-1).

wherein L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—,

k2 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a14) represents a hydrogen atom or a methyl group,

R^(a15) and R^(a16) each independently represent a hydrogen atom, amethyl group or a hydroxy group, and

o1 represents an integer of 0 to 10.

In the formula (a2-1), L^(a3) is preferably —O—, —O—(CH₂)_(f1)—CO—O—,here f1 represents an integer of 1 to 4, and more preferably —O—.

R^(a14) is preferably a methyl group.

R^(a15) is preferably a hydrogen atom.

R^(a16) is preferably a hydrogen atom or a hydroxy group.

o1 is preferably an integer of 0 to 3, and more preferably an integer of0 or 1.

Examples of the monomer from which the structural unit (a2-1) is derivedinclude monomers described in JP 2010-204646A. Among these, the monomersare preferably monomers represented by the formula (a2-1-1) to theformula (a2-1-6), more preferably structural units represented by theformula (a2-1-1) to the formula (a2-1-4), and still more preferablystructural units represented by the formula (a2-1-1) and the formula(a2-1-3) below.

Examples of monomers introducing the structural unit (a2) having thealcoholic hydroxy group include monomers described in JP 2010-204646A.

When the resin (A) contains the structural unit (a2) having thealcoholic hydroxy group, the proportion thereof is generally 1% by moleto 45% by mole, preferably 1% by mole to 40% by mole, more preferably 1%by mole to 35% by mole, and still more preferably 2% by mole to 20% bymole, with respect to the total structural units (100% by mole)constituting the resin (A).

<Structural Unit (a3)>

The lactone ring included in the structural unit (a3) may be amonocyclic compound such as β-propiolactone, γ-butyrolactone,δ-valerolactone, or a condensed ring of monocyclic lactone ring withanother ring. Examples of the lactone ring preferably includeγ-butyrolactone, amadantane lactone, or bridged ring withγ-butyrolactone.

Examples of the structural unit (a3) include structural unitsrepresented by any of the formula (a3-1), the formula (a3-2), theformula (a3-3) and the formula (a3-4). These structural units may beused as a single unit or as a combination of two or more units.

-   -   wherein L^(a4) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3        represents an integer of 1 to 7, * represents a binding site to        a carbonyl group,

R^(a18) represents a hydrogen atom or a methyl group,

R^(a21) in each occurrence represents a C₁ to C₄ aliphatic hydrocarbongroup, and

-   -   p1 represents an integer of 0 to 5,    -   L^(a5) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents an        integer of 1 to 7, * represents a binding site to a carbonyl        group,    -   R^(a19) represents a hydrogen atom or a methyl group,    -   R^(a22) in each occurrence represents a carboxy group, a cyano        group or a C₁ to C₄ aliphatic hydrocarbon group,    -   q1 represents an integer of 0 to 3,    -   L^(a6) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents an        integer of 1 to 7, * represents a binding site to a carbonyl        group,    -   R^(a20) represents a hydrogen atom or a methyl group,    -   R^(a23) in each occurrence represents a carboxy group, a cyano        group or a C₁ to C₄ aliphatic hydrocarbon group, and    -   r1 represents an integer of 0 to 3,    -   R^(a24) represents a hydrogen atom, a halogen atom or a C₁ to C₆        alkyl group that may have a halogen atom,    -   L^(a7) represents a single bond, —O—, *—O-L^(a8)-O—,        *—O-L^(a8)-CO—O—, *—O-L^(a8)-CO—O-L^(a9)-CO—O—, or        *—O-L^(a8)-O—CO-L^(a9)-O—; * represents a binding site to a        carbonyl group, and    -   L^(a9) and L^(a9) independently represents a C₁ to C₆ alkanediyl        group.

Examples of the aliphatic hydrocarbon group R^(a21), R^(a22) and R^(a23)include an alkyl group such as methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl and tert-butyl groups.

Examples of the halogen atom of R^(a24) include fluorine, chlorine,bromine or iodine atom;

Examples of the alkyl group of R^(a24) include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups,preferably a C₁ to C₄ alkyl group, more preferably a methyl or ethylgroup.

Examples of the alkyl group having a halogen atom of R^(a24) includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, tricloromethyl, tribromomethyl andtriiodomethyl groups.

Examples of the alkanediyl group of L^(a8) and L^(a9) include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl, pentane-1,4-diyl and2-methylbutane-1,4-diyl groups.

In the formulae (a3-1) to (a3-3), L^(a4) to L^(a6) is independentlypreferably —O—, *—O—(CH₂)_(k3′)—CO—O—, here k3′ represents an integer of1 to 4, more preferably —O— or *—O—CH₂—CO—O—, and still more preferably*—O—.

R^(a18) to R^(a21) is preferably a methyl group.

R^(a22) and R^(a23) are independently preferably a carboxy group, acyano group or a methyl group.

p1, q1 and r1 are independently preferably an integer of 0 to 2, andmore preferably 0 or 1.

In the formula (a3-4), R^(a24) is preferably a hydrogen atom or a C₁ toC₄ alkyl group, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

L^(a7) is preferably a single bond or *—O-L^(a8)-CO—O—, and morepreferably a single bond, —O—CH₂—CO—O— or —O—C₂H₄—CO—O—.

Examples of the monomer from which the structural unit (a3) is derivedinclude monomers described in JP 2010-204646A, monomers described inJP2000-122294A and monomers described in JP2012-41274A. Among these, thestructural units are preferably structural units represented by theformula (a3-1-1) to the formula (a3-1-4), the formula (a3-2-1) to theformula (a3-2-4), the formula (a3-3-1) to the formula (a3-3-4), theformula (a3-4-1) to the formula (a3-4-12), more preferably monomersrepresented by the formula (a3-1-1) to the formula (a3-1-2), the formula(a3-2-3), the formula (a3-2-4), the formula (a3-4-1) and the formula(a3-4-2), and still more preferably monomers represented by the formula(a3-1-1), the formula (a3-2-3) or the formula (a3-4-2) below.

When the resin (A) contains the structural units (a3), the totalproportion thereof is preferably 5% by mole to 70% by mole, morepreferably 10% by mole to 65% by mole, still more preferably 10% by moleto 60% by mole, with respect to the total structural units (100% bymole) constituting the resin (A).

The proportion each of the formula (a3-1), the formula (a3-2), theformula (a3-3) and the formula (a3-4) is preferably 5% by mole to 60% bymole, more preferably 5% by mole to 50% by mole, still more preferably10% by mole to 50% by mole, with respect to the total structural units(100% by mole) constituting the resin (A).

<Other Structural Unit (t)>

The resin (A) may include other structural unit (t) as a structural unitin addition to the structural unit (a1) and the structural unit (s).Examples of the structural unit (t) include a structural unit (a4) and astructural unit (a5) other than the structural unit (a2) and thestructural unit (a3).

When the resin (A) contains the structural unit (a4), the proportionthereof is generally 1 to 20% by mole, preferably 2 to 15% by mole, morepreferably 3 to 10% by mole, with respect to the total structural units(100% by mole) of the resin (A).

When the resin (A) contains the structural unit (a5), the proportionthereof is generally 1 to 30% by mole, preferably 2 to 20% by mole, morepreferably 3 to 15% by mole, with respect to the total structural units(100% by mole) of the resin (A).

The resin (A) may include a structural unit other than structural unitsdescribed above. Examples of the structural unit include a knownstructural unit.

The resin (A) preferably is a resin having the structural unit (a1) andthe structural unit (s), that is, a copolymer of the monomer (a1) andthe monomer (s). In this copolymer, the structural unit (a1) ispreferably at least one of the structural unit (a1-0), the structuralunit (a1-1) and the structural unit (a1-2) (preferably the structuralunit having a cyclohexyl group or a cyclopentyl group), and morepreferably is the structural unit (a1-1) or the structural unit (a1-2)(preferably the structural unit having a cyclohexyl group or acyclopentyl group).

The structural unit (s) is preferably at least one of the structuralunit (a2) or the structural unit (a3). The structural unit (a2) ispreferably the structural unit represented by the formula (a2-1). Thestructural unit (a3) is preferably at least one of structural unitsrepresented by γ-butyrolactone ring, a bridged ring havingγ-butyrolactone ring structure or adamantanelactone ring.

The proportion of the structural unit derived from the monomer having anadamantyl group (in particular, the structural unit (a1-1)) in the resin(A) is preferably 15% by mole or more with respect to the structuralunits (a1). As the mole ratio of the structural unit derived from themonomer having an adamantyl group increases within this range, the dryetching resistance of the resulting resist improves.

The structural unit constituting the resin (A) may be used as a singlestructural unit or as a combination of two or more structural units. Theresin (A) can be produced by a known polymerization method, for example,radical polymerization method, using a monomer introducing thestructural unit. The proportion of the structural unit in the resin (A)can be adjusted by amount of a monomer used in polymerization.

The weight average molecular weight of the resin (A) is preferably 2,000or more (more preferably 2,500 or more, and still more preferably 3,000or more), and 50,000 or less (more preferably 30,000 or less, and stillmore preferably 15,000 or less).

The weight average molecular weight is a value determined by gelpermeation chromatography.

When a resist composition contain the resin (X), the proportion thereofis preferably 1 to 60 parts by mass, more preferably 3 to 50 parts bymass, and still more preferably 5 to 40 parts by mass, in particularpreferably 7 to 30 parts by mass, with respect to the resin (A) (100parts by mass).

The total proportion of the resin (A) and the resin (X) is preferably80% by mass to 99% by mass, and more preferably 90% by mass to 99% bymass, with respect to the total solid proportion of the resistcomposition.

The solid proportion of the resist composition can be measured with aknown analytical method such as, for example, liquid chromatography andgas chromatography.

<Resin Other Than Resin (A) and Resin (X)>

A resist composition of the present invention may further includeanother resin in addition to the resin (A) and the resin (X). Examplesof the resin include a resin having neither the structural unit (I) northe structural unit (a), for example, a resin consisting of thestructural units (s).

A resin other than the resin (A) and the resin (X) is preferably a resinhaving neither the structural unit (I) nor the structural unit (a1) butincluding the structural unit (a4) (which is sometimes referred to as“resin (Y)”). In the resin (Y), the proportion of the structural unit(a4) is preferably 40% by mole or more, and more preferably 45% by moleor more, and still more preferably 50% by mole or more with respect tothe total structural units (100% by mole) constituting the resin (Y).

Examples of the structural unit in which the resin (Y) may furthercontain include the structural unit (a2), the structural unit (a3) andother structural unit derived from a known monomer.

The weight average molecular weight of the resin (Y) is preferably 8,000or more (more preferably 10,000 or more), and 80,000 or less (morepreferably 60,000 or less).

When a resist composition contain the resin (Y), the proportion thereofis preferably 1 to 60 parts by mass, more preferably 1 to 50 parts bymass, and still more preferably 1 to 40 parts by mass, in particularpreferably 2 to 30 parts by mass, with respect to the resin (Y) (100parts by mass).

The total proportion of the resins (A), (X) and (Y) is preferably 80% bymass to 99% by mass, and more preferably 90% by mass to 99% by mass,with respect to the total solid proportion of the resist composition.

<Acid Generator (B)>

The acid generator (B) may be an ionic acid generator or a non-ionicacid generator. The acid generator (B) may be used any an ionic acidgenerator and a non-ionic acid generator. Examples of the nonioniccompounds for the acid generator include organic halogenated compounds;sulfonate esters, e.g. 2-nitrobenzylester, aromatic sulfonates,oximesulfonate, N-sulfonyloxyimide, sulfonyloxyketone, anddiazonaphtoquione 4-sulfonate; sulfones, e.g., disulfone, ketosulfone,and sulfonium diazomethane. The ionic compounds for the acid generatorinclude onium salts having an onium cation, e.g., diazonium salts,phosphonium salts, sulfonium salts and iodonium salts. Examples of theanions of onium salt include a sulfonic acid anion, a sulfonylimideanion, sulfonylmethide anion.

As the acid generator, the compounds giving an acid by radiation can beused, which are mentioned in JP63-26653A1, JP55-164824A1, JP62-69263A1,JP63-146038A1, JP63-163452A1, JP62-153853A1, JP63-146029A1, U.S. Pat.No. 3,779,778B1, U.S. Pat. No. 3,849,137B1, DE3914407 and EP126,712A1.The acid generator for the photoresist composition can be produced bythe method described in the above-mentioned documents.

The acid generator is preferably a fluorine-containing compound, morepreferably salt represented by the formula (B1) (which is sometimesreferred to as “acid generator (B1)”):

wherein Q¹ and Q² respectively represent a fluorine atom or a C₁ to C₆perfluoroalkyl group,

L^(b1) represents a divalent C₁ to C₂₄ saturated hydrocarbon group wherea methylene group may be replaced by an oxygen atom or a carbonyl groupand where a hydrogen atom may be replaced by a hydroxyl group orfluorine atom, and

Y represents an optionally substituted C₃ to C₁₈ alicyclic hydrocarbongroup where a methylene group may be replaced by an oxygen atom, acarbonyl group or a sulfonyl group, and

Z represents an organic cation.

Examples of the perfluoroalkyl group of Q¹ and Q² includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl and perfluorohexyl groups.

Q¹ and Q² independently are preferably trifluoromethyl or fluorine atom,and both of Q¹ and Q² are preferably a fluorine atom.

Examples of the divalent saturated hydrocarbon group of L^(b1) includeany of a chain or a branched alkanediylgroup, a divalent mono- or apoly-alicyclic saturated hydrocarbon group, and a combination thereof.

Specific examples of the chain alkanediyl group include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl,dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl,pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diylgroups.

Specific examples of the branched chain alkanediyl group includeethane-1,1-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-2,2-diyl,pentane-1,4-diyl, pentane-2,4-diyl, 2-methylpropane-1,3-diyl,2-methylpropane-1,2-diyl and 2-methylbutane-1,4-diyl groups.

Specific examples of the mono-alicyclic saturated hydrocarbon groupinclude a cycloalkanediyl group such as cyclobutan-1,3-diyl,cyclopentan-1,3-diyl, cyclohexane-1,4-diyl and cyclooctan-1,5-diylgroups.

Specific examples of the poly-alicyclic saturated hydrocarbon groupinclude norbornane-1,4-diyl, norbornane-2,5-diyl, adamantane-1,5-diyland adamantane-2,6-diyl groups.

Examples of the saturated hydrocarbon group of L^(b1) in which amethylene group has been replaced by oxygen atom or a carbonyl groupinclude groups represented by the formula (b1-1) to the formula (b1-3)below:

wherein L^(b2) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L^(b3) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b2)and L^(b3) is 22 or less;

L^(b4) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b5) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b4)and L^(b5) is 22 or less;

L^(b6) represents a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

L^(b7) represents a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b6)and L^(b1) is 23 or less, and

* represents a binding site to —Y.

In formula (b1-1) to formula (b1-3), when a methylene group has beenreplaced by an oxygen atom or a carbonyl group, the carbon number of thesaturated hydrocarbon group corresponds to the number of the carbon atombefore replacement.

Examples of the divalent saturated hydrocarbon group are the sameexamples as the divalent saturated hydrocarbon group of L^(b1).

L^(b2) is preferably a single bond.

L^(b3) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b4) is preferably a C₁ to C₈ divalent saturated hydrocarbon groupwhere a hydrogen atom may be replaced by a fluorine atom.

L^(b5) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b6) is preferably a single bond or a C₁ to C₄ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom.

L^(b7) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and where a methylene group may be replaced byan oxygen atom or a carbonyl group.

Among these, the group represented by the formula (b1-1) or the formula(b1-3) is preferred.

Examples of the divalent group represented by the formula (b1-1) includegroups represented by the formula (b1-4) to the formula (b1-8) describedbelow:

wherein L^(b8) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom or a hydroxy group;

L^(b9) represents a C₁ to C₂₀ divalent saturated hydrocarbon group;

L^(b10) represents a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b9)and L^(b10) is 20 or less;

L^(b11) represents a C₁ to C₂₁ divalent saturated hydrocarbon group;

L^(b12) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b11)and L^(b12) is 21 or less;

L^(b13) represents a C₁ to C₁₉ divalent saturated hydrocarbon group;

L^(b14) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group;

L^(b15) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b13),L^(b14) and L^(b15) is 19 or less;

L^(b16) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b17) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b18) represents a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b16),L^(b17) and L^(b18) is 19 or less.

L^(b8) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b9) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b10) is preferably a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b11) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b12) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b13) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b14) is preferably a single bond or a C₁ to C₆ divalent saturatedhydrocarbon group.

L^(b15) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b16) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b17) is preferably a C₁ to C₆ divalent saturated hydrocarbon group.

L^(b18) is preferably a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₄divalent saturated hydrocarbon group.

Examples of the divalent group represented by the formula (b1-3) includegroups represented by the formula (b1-9) to the formula (b1-11)described below:

wherein L^(b19) represents a single bond or a C₁ to C₂₃ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L²⁰ represent a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b19)and L^(b20) is 23 or less;

L^(b21) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b22) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b23) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b21),L^(b22) and L^(b23) is 21 or less;

L^(b24) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b25) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b26) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b24),L^(b25) and L^(b26) is 21 or less.

In formula (b1-9) to formula (b1-11), when a hydrogen atom has beenreplaced by an acyloxy group, the carbon number of the saturatedhydrocarbon group corresponds to the number of the carbon atom, CO and Oin addition to the carbon number of the saturated hydrocarbon group.

For formula (b1-9) to formula (b1-11), examples of the divalentsaturated hydrocarbon group include an alkanediyl and a monocyclic orpolycyclic divalent saturated hydrocarbon group, and a combination oftwo or more such groups.

Examples of the acyloxy group include acetyloxy, propionyloxy,butyryloxy, cyclohexyl carbonyloxy and adamantyl carbonyloxy groups.

Examples of the acyloxy group having a substituent include oxoadamantylcarbonyloxy, hydroxyadamantyl carbonyloxy, oxocyclohexyl carbonyloxy andhydroxycyclohexyl carbonyloxy groups.

Examples of the group represented by the formula (b1-4) include thefollowing ones.

Examples of the group represented by the formula (b1-5) include thefollowing ones.

Examples of the group represented by the formula (b1-6) include thefollowing ones.

Examples of the group represented by the formula (b1-7) include thefollowing ones.

Examples of the group represented by the formula (b1-8) include thefollowing ones.

Examples of the group represented by the formula (b1-2) include thefollowing ones.

Examples of the group represented by the formula (b1-9) include thefollowing ones.

Examples of the group represented by the formula (b1-10) include thefollowing ones.

Examples of the group represented by the formula (b1-11) include thefollowing ones.

Examples of the monovalent alicyclic hydrocarbon group of Y includegroups represented by the formula (Y1) to the formula (Y11).

Examples of the monovalent alicyclic hydrocarbon group of Y in which amethylene group has been replaced by an oxygen atom, a carbonyl group ora sulfonyl group include groups represented by the formula (Y12) to theformula (Y27).

Among these, the alicyclic hydrocarbon group is preferably any one ofgroups represented by the formula (Y1) to the formula (Y19), morepreferably any one of groups represented by the formula (Y11), (Y14),(Y15) or (Y19), and still more preferably group represented by theformula (Y11) or (Y14).

Examples of the substituent for the alicyclic group represented by Yinclude a halogen atom, a hydroxyl group, a C₁ to C₁₂ alkyl group, ahydroxy group-containing C₁ to C₁₂ alkyl group, a C₃ to C₁₆ monovalentalicyclic hydrocarbon group, a C₁ to C₁₂ alkoxy group, a C₆ to C₁₈monovalent aromatic hydrocarbon group, a C₇ to C₂₁ aralkyl group, a C₂to C₄ acyl group, a glycidyloxy group and —(CH₂)_(j2)—O—CO—R^(b1)— inwhich R^(b1) represents an C₁ to C₁₆ alkyl group, a C₃ to C₁₆ monovalentalicyclic hydrocarbon group, or a C₆ to C₁₈ monovalent aromatichydrocarbon group, and j2 represents an integer of 0 to 4.

Examples of the hydroxy group-containing alkyl group includehydroxymethyl and hydroxyethyl groups

Examples of the alkoxyl group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxygroups.

Examples of the monovalent aromatic hydrocarbon group include an arylgroup such as phenyl, naphthyl, anthryl, p-methylphenyl,p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl,biphenyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

Examples of the aralkyl group include benzyl, phenethyl, phenylpropyl,naphthylmethyl and naphthylethyl groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of Y include the groups below. * represents a binding site toL^(b1).

Y is preferably a C₃ to C₁₈ monovalent alicyclic hydrocarbon group whichmay have a substituent, more preferably an adamantyl group which mayhave a substituent and one or more methylene group contained in theadamantyl group may be replaced with an oxygen atom, a carbonyl group ora sufonyl group, and still more preferably an adamantyl group, ahydroxyadamantyl group or an oxoadamantyl group.

The sulfonic acid anion in the salt represented by the formula (B1) ispreferably an anions represented by the formula (B1-A-1) to the formula(B1-A-33), and more preferably an anions represented by the formula(B1-A-1) to the formula (B1-A-4), the formula (B1-A-9), the formula(B1-A-10), the formula (B1-A-24) to the formula (B1-A-33), below.

In the formula (B1-A-1) to the formula (B1-A-33), R^(i2) to R^(i7)independently represent, for example, a C₁ to C₄ alkyl group, andpreferably methyl or ethyl group, R^(i8) represent, for example, a C₁ toC₁₂ aliphatic hydrocarbon group, preferably a C₁ to C₄ alkyl group, a C₅to C₁₂ monovalent alicyclic hydrocarbon group or a group formed by acombination thereof, more preferably a methyl, ethyl group, cyclohexylgroup or adamantyl group. L⁴ represents a single bond or a C₁ to C₄alkanediyl group. Q¹ and Q² represent the same meaning as defined above.

Specific examples of the sulfonic acid anion in the salt represented bythe formula (B1) include anions mentioned in JP2010-204646A1.

Among these, preferred examples of the sulfonic acid anion for the saltrepresented by the formula (B1) include anions represented by theformulae (B1a-1) to (B1a-15).

Among them, preferred examples of the sulfonic acid anion include anionsrepresented by the formulae (B1a-1) to (B1a-3) and (B1a-7) to (B1a-15).

Examples of the organic cation represented by Z⁺ include an organiconium cation such as an organic sulfonium cation, an organic iodoniumcation, an organic ammonium cation, a benzothiazolium cation and anorganic phosphonium cation, and an organic sulfonium cation and anorganic iodonium cation are preferred, and an arylsulfonium cation ismore preferred.

Z⁺ of the formula (B1) is preferably represented by any of the formula(b2-1) to the formula (b2-4):

wherein R^(b4), R^(b5) and R^(b6) independently represent a C₁ to C₃₀aliphatic hydrocarbon group, a C₃ to C₃₆ alicyclic hydrocarbon group ora C₆ to C₃₆ aromatic hydrocarbon group, a hydrogen atom contained in analiphatic hydrocarbon group may be replaced by a hydroxy group, a C₁ toC₁₂ alkoxy group, a C₃ to C₁₂ alicyclic hydrocarbon group or a C₆ to C₁₈aromatic hydrocarbon group, a hydrogen atom contained in an alicyclichydrocarbon group may be replaced by a halogen atom, a C₁ to C₁₈aliphatic hydrocarbon group, a C₂ to C₄ acyl group or a glycidyloxygroup, a hydrogen atom contained in an aromatic hydrocarbon group may bereplaced by a halogen atom, a hydroxy group or a C₁ to C₁₂ alkoxy group,or R^(b4) and R^(b5) may be bonded together with a sulfur atom bondedthereto to form a sulfur-containing ring, a methylene group contained inthe ring may be replaced by an oxygen atom, a sulfur atom or a carbonylgroup;

R^(b7) and R^(b8) in each occurrence independently represent a hydroxygroup, a C₁ to C₁₂ aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxygroup,

m2 and n2 independently represent an integer of 0 to 5;

R^(b9) and R^(b10) independently represent a C₁ to C₃₆ aliphatichydrocarbon group or a C₃ to C₃₆ alicyclic hydrocarbon group, or R^(b9)and R^(b10) may be bonded together with a sulfur atom bonded thereto toform a sulfur-containing ring, and a methylene group contained in thering may be replaced by an oxygen atom, sulfur atom or a carbonyl group;

R^(b11) represents a hydrogen atom, a C₁ to C₃₆ aliphatic hydrocarbongroup, a C₃ to C₃₆ alicyclic hydrocarbon group or a C₆ to C₁₈ aromatichydrocarbon group;

R^(b12) represents a C₁ to C₁₂ aliphatic hydrocarbon group, a C₃ to C₁₈alicyclic hydrocarbon group and a C₆ to C₁₈ aromatic hydrocarbon group,a hydrogen atom contained in an aliphatic hydrocarbon group may bereplaced by a C₆ to C₁₈ aromatic hydrocarbon group, and a hydrogen atomcontained in an aromatic hydrocarbon group may be replaced by a C₁ toC₁₂ alkoxy group or a C₁ to C₁₂ alkyl carbonyloxy group;

R^(b11) and R^(b12) may be bonded together with —CH—CO— bonded theretoto form a ring, and a methylene group contained in the ring may bereplaced by an oxygen atom, sulfur atom or a carbonyl group;

R^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) in eachoccurrence independently represent a hydroxy group, a C₁ to C₁₂aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxy group;

L^(b13) represents —S— or —O—;

o2, p2, s2 and t2 independently represent an integer of 0 to 5;

q2 or r2 independently represent an integer of 0 to 4; and

u2 represents an integer of 0 or 1.

Examples of the aliphatic group preferably include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-octyl and 2-ethylhexyl groups. Among these, the aliphatic hydrocarbongroup of R^(b9) to R^(b12) is preferably a C₁ to C₁₂ aliphatichydrocarbon group.

Examples of the alicyclic hydrocarbon group preferably includemonocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecylgroups; and polycyclic hydrocarbon groups such as decahydronaphtyl,adamantyl and norbornyl groups as well as groups below.

Among these, the alicyclic hydrocarbon group of R^(b9) to R^(b12) ispreferably a C₃ to C₁₈ alicyclic group, and more preferably a C₄ to C₁₂alicyclic hydrocarbon group.

Examples of the alicyclic hydrocarbon group where a hydrogen atom may bereplaced by an aliphatic hydrocarbon group include methylcyclohexyl,dimethylcyclohexyl, 2-alkyladamantane-2-yl, methylnorbornyl andisobornyl groups. In the alicyclic hydrocarbon group where a hydrogenatom may be replaced by an aliphatic hydrocarbon group, the total carbonnumber of the alicyclic hydrocarbon group and the aliphatic hydrocarbongroup is preferably 20 or less.

Examples of the aromatic hydrocarbon group preferably include an arylgroup such as phenyl, tolyl, xylyl, cumenyl, mesityl, p-ethylphenyl,p-tert-butylphenyl, p-cyclohexylphenyl, p-adamantylphenyl, biphenyl,naphthyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

When the aromatic hydrocarbon includes an aliphatic hydrocarbon group oran alicyclic hydrocarbon group, a C₁ to C₁₈ aliphatic hydrocarbon groupor a C₃ to C₁₈ alicyclic hydrocarbon group is preferred.

Examples of the aromatic hydrocarbon group where a hydrogen atom may bereplaced by an alkoxy group include a p-methoxyphenyl group.

Examples of the aliphatic hydrocarbon group where a hydrogen atom may bereplaced by an aromatic hydrocarbon group include an aralkyl group suchas benzyl, phenethyl phenylpropyl, trityl, naphthylmethyl andnaphthylethyl groups.

Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, and dodecyloxy groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkylcarbonyloxy group include methylcarbonyloxy,ethylcarbonyloxy, n-propylcarbonyloxy, isopropylcarbonyloxy,n-butylcarbonyloxy, sec-butylcarbonyloxy, tert-butyl carbonyloxy,pentylcarbonyloxy, hexylcarbonyloxy, octylcarbonyloxy and2-ethylhexylcarobonyloxy groups.

The sulfur atom-containing ring which is formed by R^(b4) and R^(b5) maybe a monocyclic or polycyclic one, which may be an aromatic ornon-aromatic one, and which may be a saturated or unsaturated one. Thering is preferably a ring having 3 to 18 carbon atoms, and morepreferably a ring having 4 to 13 carbon atoms. Examples of the sulfuratom-containing ring include a 3- to 12-membered ring, preferably a 3-to 7-membered ring, examples thereof include rings below.

Examples of the ring formed by R^(b9) and R^(b10) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring. Examples of the ring include thiolane-1-iumring (tetrahydrothiophenium ring), thian-1-ium ring and1,4-oxathian-4-ium ring.

Examples of the ring formed by R^(b11) and R^(b12) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring. Examples of the ring include oxocycloheptanering, oxocyclohexane ring, oxonorbornane ring and oxoadamantane ring.

Among the cations represented by the formula (b2-1) to the formula(b2-4), the cation represented by the formula (b2-1) is preferred, thecation represented by the formula (b2-1-1) is more preferred, andtriphenyl sulfonium cation (v2=w2=x2=0 in the formula (b2-1-1)),diphenyl sulfonium cation (v2=w2=0, x2=1, and R^(b21) is a methyl groupin the formula (b2-1-1)), and tritolyl sulfonium cation (v2=w2=x2=1,R^(b19), R^(b20) and R^(b21) are a methyl group in the formula (b2-1-1))are still more preferred:

wherein R^(b19), R^(b20) and R^(b21) in each occurrence independentlyrepresent a halogen atom, a hydroxy group, a C₁ to C₁₈ aliphatichydrocarbon group, a C₃ to C₁₈ alicyclic hydrocarbon group or a C₁ toC₁₂ alkoxy group, or two of R^(b19), R^(b20) and R^(b21) may be bondedtogether to form a sulfur-containing ring.

In the formula (b2-1-1), the sulfur-containing ring formed by two ofR^(b19), R^(b20) and R^(b21) may be monocyclic or polycyclic ring. Thering may be aromatic or non-aromatic ring. The ring may be saturated orunsaturated ring. The ring may have a further more sulfur atom and/or anoxygen atom.

The alkyl group of R^(b19), R^(b20) and R^(b21) is preferably a C₁ toC₁₂ aliphatic hydrocarbon group. The alicyclic hydrocarbon group ofR^(b19), R^(b20) and R^(b21) is preferably a C₄ to C₁₈ alicyclichydrocarbon group,

R^(b19), R^(b20) and R^(b21) each independently preferably represent ahalogen atom (and more preferably fluorine atom), a hydroxy group, a C₁to C₁₂ aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxy group; or twoof R^(b19), R^(b20) and R^(b21) preferably are bonded together to form asulfur-containing ring, and

v2, w2 and x2 independently represent preferably 0 or 1.

Specific examples of the organic cations represented by the formula(b2-1) to the formula (b2-4) and the formula (b2-1-1) include, forexample, compounds described in JP2010-204646A.

The acid generator (B1) is generally a compound which consists of theabove sulfonate anion with an organic cation. The above sulfonic acidanion and the organic cation may optionally be combined. Preferredcombination is a combination of any of the anion represented by theformula (B1a-1) to the formula (B1a-3), the formula (B1a-7) to theformula (B1a-15) and the cation represented by the formula (b2-1-1) orthe formula (b2-3).

Preferred acid generators (B1) are represented by the formula (B1-1) tothe formula (B1-30). Among these, the formulae (B1-1), (B1-2), (B1-3),(B1-5), (B1-6), (B1-7), (B1-11), (B1-12), (B1-13), (B1-14), (B1-17),(B1-20), (B1-21), (B1-23), (B1-24), (B1-25), (B1-26) and (B1-29) whichcontain arylsulfonium cation are preferred.

The proportion of the acid generator (B1) is preferably 30% by mass ormore, and 100% by mass or less, more preferably 50% by mass or more, and100% by mass or less, and still more preferably substantially 100% byweight with respect to 100% by mass of total acid generator (B).

In the resist composition of the present invention, the proportion ofthe acid generator (B) is preferably 1 parts by mass or more and morepreferably 3 parts by mass or more, and preferably 30 parts by mass orless and more preferably 25 parts by mass or less with respect to 100parts by mass of the resin (A).

In the resist composition of the present invention, the acid generator(B) may be used as a single salt or as a combination of two or more ofsalts.

<Solvent (E)>

The proportion of a solvent (E) is generally 90% by mass or more,preferably 92% by mass or more, and more preferably 94% by mass or more,and also preferably 99% by mass or less, and more preferably 99.9% bymass or less. The proportion of the solvent (E) can be measured with aknown analytical method such as liquid chromatography and gaschromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate and propylene glycolmonomethyl ether acetate; glycol ethers such as propylene glycolmonomethyl ether; esters such as ethyl lactate, butyl acetate, amylacetate and ethyl pyruvate; ketones such as acetone, methyl isobutylketone, 2-heptanone and cyclohexanone; and cyclic esters such asγ-butyrolactone. These solvents may be used as a single solvent or as amixture of two or more solvents.

<Quencher (C)>

The resist composition of the present invention may contain a quenchersuch as a basic nitrogen-containing organic compound and a salt whichgenerates an acid weaker in acidity than an acid generated from the acidgenerator.

The proportion of the quencher is preferably 0.01% by mass to 5% by masswith respect to the total solid components of the resist composition.

Examples of the basic nitrogen-containing organic compound include anamine and ammonium salts. The amine may be an aliphatic amine or anaromatic amine. The aliphatic amine includes any of a primary amine,secondary amine and tertiary amine

Specific examples of the amine include 1-naphtylamine, 2-naphtylamine,aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine,didecylamine, triethylamine, trimethylamine, tripropylamine,tributylamine, tripentylamine, trihexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, methyldibutylamine,methyldipentylamine, methyldihexylamine, methyldicyclohexylamine,methyldiheptylamine, methyldioctylamine, methyldinonylamine,methyldidecylamine, ethyldibutylamine, ethyldipentylamine,ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine,ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine,tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylene diamine, hexamethylene diamine,4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane,di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine and bipyridine. Among these,diisopropylaniline is preferred, particularly 2,6-diisopropylaniline ismore preferred.

Specific examples of the ammonium salt include tetramethylammoniumhydroxide, tetraisopropylammonium hydroxide, tetrabutylammoniumhydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethyl ammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate and choline.

<Weak Acid Salt>

The salt generating an acid which is lower in acidity than an acidgenerated from the acid generator (B) is sometimes referred to as “weakacid salt”. The “acidity” can be represented by acid dissociationconstant, pKa, of an acid generated from a weak acid salt. Examples ofthe weak acid salt include a salt generating an acid of pKa representsgenerally more than −3, preferably −1 to 7, and more preferably 0 to 5.

Specific examples of the weak acid salt include the following salts, thesalt of formula (D), and salts as disclosed in JP2012-229206A1,JP2012-6908A1, JP2012-72109A1, JP2011-39502A1 and JP2011-191745A1,preferably the salt of formula (D).

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlyrepresent a C₁ to C₁₂ hydrocarbon group, a C₁ to C₆ alkoxyl group, a C₂to C₇ acyl group, a C₂ to C₇ acyloxy group, a C₂ to C₇ alkoxycarbonylgroup, a nitro group or a halogen atom;

m′ and n′ each independently represent an integer of 0 to 4.

Examples of the hydrocarbon group of R^(D1) and R^(D2) include any of analiphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group and a combination thereof.

Examples of the aliphatic hydrocarbon group include an alkyl group suchas methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl,pentyl, hexyl and nonyl groups.

The alicyclic hydrocarbon group is any one of monocyclic or polycyclichydrocarbon group, and saturated or unsaturated hydrocarbon group.Examples thereof include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl and cyclododecyl groups;adamantyl and norbornyl groups. The alicyclic hydrocarbon group ispreferably saturated hydrocarbon group.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, 1-naphthyl, 2-naphthyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl,4-butylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl,anthryl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the combination thereof include an alkyl-cycloalkyl, acycloalkyl-alkyl, aralkyl (e.g., phenylmethyl, 1-phenylethyl,2-phenylethyl, 1-phenyl-1-propyl, 1-phenyl-2-propyl, 2-phenyl-2-propyl,3-phenyl-1-propyl, 4-phenyl-1-butyl, 5-phenyl-1-pentyl and6-phenyl-1-hexyl groups) groups.

Examples of the alkoxyl group include methoxy and ethoxy groups.

Examples of the acyl group include acetyl, propanonyl, benzoyl andcyclohexanecarbonyl groups.

Examples of the acyloxy group include a group in which oxy group (—O—)bonds to an acyl group.

Examples of the alkoxycarbonyl group include a group in which thecarbonyl group (—CO—) bonds to the alkoxy group.

Example of the halogen atom is a chlorine atom, a fluorine atom andbromine atom.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlypreferably represent a C₁ to C₈ alkyl group, a C₃ to C₁₀ cycloalkylgroup, a C₁ to C₆ alkoxyl group, a C₂ to C₄ acyl group, a C₂ to C₄acyloxy group, a C₂ to C₄ alkoxycarbonyl group, a nitro group or ahalogen atom.

m′ and n′ independently preferably represent an integer of 0 to 3, morepreferably an integer of 0 to 2, and more preferably 0.

Specific examples of the salt of the formula (D) include compoundsbelow.

The salt of the formula (D) can be produced by a method described in“Tetrahedron Vol. 45, No. 19, p6281-6296”. Also, commercially availablecompounds can be used as the salt of the formula (D).

In the resist composition of the present invention, the proportion ofthe salt which generates an acid weaker in acidity than an acidgenerated from the acid generator, for example, the salt of the formula(D) is preferably 0.01% by mass to 5% by mass, more preferably 0.01% bymass to 4% by mass, and still more preferably 0.01% by mass to 3% bymass with respect to total solid components of the resist composition.

<Other Ingredient>

The resist composition can also include other ingredient (which issometimes referred to as “other ingredient (F)”). Examples of the otheringredient (F) include various additives such as sensitizers,dissolution inhibitors, surfactants, stabilizers, and dyes, as needed.

<Preparing the Resist Composition>

The present resist composition can be prepared by mixing the resin (A),the compound (a), the acid generator (B), the resin other than the resin(A), the quencher, the solvent (E) and the other ingredient (F), asneeded. There is no particular limitation on the order of mixing. Themixing may be performed in an arbitrary order. The temperature of mixingmay be adjusted to an appropriate temperature within the range of 10 to40° C., depending on the kinds of the resin and solubility in thesolvent (E) of the resin. The time of mixing may be adjusted to anappropriate time within the range of 0.5 to 24 hours, depending on themixing temperature. There is no particular limitation to the tool formixing. An agitation mixing may be adopted.

After mixing the above ingredients, the present resist compositions canbe prepared by filtering the mixture through a filter having about 0.003to 0.2 μm pore diameter.

<Method for Producing Resist Pattern>

The method for producing a resist pattern of the present inventionincludes the steps of:

(1) applying the resist composition of the present invention onto asubstrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

Applying the resist composition onto the substrate can generally becarried out through the use of a resist application device, such as aspin coater known in the field of semiconductor microfabricationtechnique. Examples of the substrate include inorganic substrates suchas silicon wafer. The substrate may be washed, and an organicantireflection film may be formed on the substrate by use of acommercially available antireflection composition, before theapplication of the resist composition.

The solvent evaporates from the resist composition and a compositionlayer with the solvent removed is formed. Drying the applied compositionlayer, for example, can be carried out using a heating device such as ahotplate (so-called “prebake”), a decompression device, or a combinationthereof. The temperature is preferably within the range of 50 to 200° C.The time for heating is preferably 10 to 180 seconds. The pressure ispreferably within the range of 1 to 1.0×10⁵ Pa.

The composition layer thus obtained is generally exposed using anexposure apparatus or a liquid immersion exposure apparatus. Theexposure is generally carried out using with various types of exposurelight source, such as irradiation with ultraviolet lasers, i.e., KrFexcimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193nm), F₂ excimer laser (wavelength: 157 nm), irradiation with harmoniclaser light of far-ultraviolet or vacuum ultra violetwavelength-converted laser light from a solid-state laser source (YAG orsemiconductor laser or the like), or irradiation with electron beam orEUV or the like. In the specification, such exposure to radiation issometimes referred to be collectively called as exposure. The exposureis generally carried out through a mask that corresponds to the desiredpattern. When electron beam is used as the exposure light source, directwriting without using a mask can be carried out.

After exposure, the composition layer is subjected to a heat treatment(so-called “post-exposure bake”) to promote the deprotection reaction.The heat treatment can be carried out using a heating device such as ahotplate. The heating temperature is generally in the range of 50 to 200degree C., preferably in the range of 70 to 150 degree C.

The developing of the baked composition film is usually carried out witha developer using a development apparatus. Developing can be conductedin the manner of dipping method, paddle method, spray method and dynamicdispensing method. Temperature for developing is generally 5 to 60degree C. The time for developing is preferably 5 to 300 seconds.

The photoresist pattern obtained from the photoresist composition may bea positive one or a negative one by selecting suitable developer.

The development for obtaining a positive photoresist pattern is usuallycarried out with an alkaline developer. The alkaline developer to beused may be any one of various alkaline aqueous solution used in theart. Generally, an aqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. The surfactant may be contained in thealkaline developer.

After development, the resist pattern formed is preferably washed withultrapure water, and the residual water remained on the resist film oron the substrate is preferably removed therefrom.

The development for obtaining a negative photoresist pattern is usuallycarried out with a developer containing an organic solvent. The organicsolvent to be used may be any one of various organic solvents used inthe art, examples of which include ketone solvents such as 2-hexanone,2-heptanone; glycol ether ester solvents such as propylene glycolmonomethyl ether acetate; ester solvents such as the butyl acetate;glycol ether solvents such as the propylene glycol monomethyl ether;amide solvents such as N,N-dimethylacetamide; aromatic hydrocarbonsolvents such as anisole.

In the developer containing an organic solvent, the amount of organicsolvents is preferably 90% by mass to 100% by mass, more preferably 95%by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of organic solvents.

Among these, the developer containing an organic solvent preferablycontains butyl acetate and/or 2-heptanone. In the developer containingan organic solvent, the total amount of butyl acetate and 2-heptanone ispreferably 50% by mass to 100% by mass of the developer, more preferably90% by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of butyl acetate and/or 2-heptanone.

Developers containing an organic solvent may contain a surfactant. Also,the developer containing an organic solvent may include a little water.

The developing with a developer containing an organic solvent can befinished by replacing the developer by another solvent.

After development, the photoresist pattern formed is preferably washedwith a rinse agent. Such rinse agent is not unlimited provided that itdoes not detract a photoresist pattern. Examples of the agent includesolvents which contain organic solvents other than the above-mentioneddevelopers, such as alcohol agents or ester agents.

After washing, the residual rinse agent remained on the substrate orphotoresist film is preferably removed therefrom.

<Application>

The resist composition of the present invention is useful for excimerlaser lithography such as with ArF, KrF, electron beam (EB) exposurelithography or extreme-ultraviolet (EUV) exposure lithography, and ismore useful for electron beam (EB) exposure lithography, ArF excimerlaser exposure lithography and extreme-ultraviolet (EUV) exposurelithography.

The resist composition of the present invention can be used insemiconductor microfabrication.

EXAMPLES

The present invention will be described more specifically by way ofexamples, which are not construed to limit the scope of the presentinvention.

All percentages and parts expressing the content or amounts used in theExamples and Comparative Examples are based on mass, unless otherwisespecified.

The weight average molecular weight is a value determined by gelpermeation chromatography.

Device: HLC-8120GPC model (Tosoh Co. Ltd.)

Column: TSK gel Multipore HXL-M×3+guardcolumn (Tosoh Co. Ltd.)

Eluant: tetrahydrofuran

Flow rate: 1.0 mL/min.

Detecting device: RI detector

Column temperature: 40° C.

Injection amount: 100 μL

Standard material for calculating molecular weight: standard polystylene(Tosoh Co. ltd.)

Structures of compounds were determined by mass spectrometry (LiquidChromatography: 1100 Type, manufactured by AGILENT TECHNOLOGIES LTD.,Mass Spectrometry: LC/MSD Type, manufactured by AGILENT TECHNOLOGIESLTD.). The value of the peak in the mass spectrometry is referred to as“MASS”.

Example 1: Synthesis of the Compound Represented by the Formula (I-1)

Into a reactor, 21.2 parts of the compound represented by the formula(I-1-a), 106 parts of chloroform, 6.98 parts of pyridine, 1.96 parts ofdimethylaminopyridine, 20.12 parts of the compound represented by theformula (I-1-b) and 16.91 parts of the compound represented by theformula (I-1-c) were charged and stirred at 23 degree C. for 5 hours.Then, 350 parts of chloroform was added to the resulting solution, andthen 65 parts of 5% hydrochloric acid was added, and the mixture wasstirred at 23 degree C. for 30 minutes. Then, the mixture was left stillto separate an organic layer. To the obtained organic layer, 170 partsof ion exchanged water was added, and the obtained mixture was stirredat 23 degree C. for 30 minutes, followed by separating an organic layerto wash with water. The washing step with water was conducted six times.The washed organic layer was concentrated and purified with columnchromatography [silica gel 60N spherical shape, neutral, 100-210 μm,solvent: mixture of n-heptane and ethyl acetate (weight ratio 10/1),manufactured by Kanto Chem. Ltd.] to obtain 28.64 parts of the compoundrepresented by formula (I-1).

MS (mass spectrography): 510.2 (molecular ion peak)

Example 2: Synthesis of the Compound Represented by the Formula (I-12)

Into a reactor, 24 parts of the compound represented by the formula(I-1-b), 120 parts of tetrahydrofuran, 7.90 parts of pyridine and 11.28parts of the compound represented by the formula (I-12-a) were chargedand stirred at 23 degree C. for 3 hours. Then, 240 parts of n-heptanewas added to the resulting solution, and then 73 parts of 5%hydrochloric acid was added, and the mixture was stirred at 23 degree C.for 30 minutes. Then, the mixture was left still to separate an organiclayer. To the obtained organic layer, 120 parts of ion exchanged waterwas added, and the obtained mixture was stirred at 23 degree C. for 30minutes, followed by separating an organic layer to wash with water. Thewashing step was conducted six times. The washed organic layer wasconcentrated to obtain 29.47 parts of the compound represented byformula (I-12-c).

Into a reactor, 10 parts of the compound represented by the formula(I-12-d), 50 parts of dimethylformamide, 4.79 parts of potassiumcarbonate and 1.15 parts of potassium iodide were charged and stirred,and then 28.35 parts of the compound represented by the formula (I-12-c)was added thereto and the obtained mixture was stirred at 23 degree C.for 5 hours. Then, 200 parts of chloroform was added to the resultingsolution, and then 25 parts of 5% hydrochloric acid was added, and themixture was stirred 23 degree C. for 30 minutes. Then, the mixture wasleft still to separate an organic layer. 100 parts of ion exchangedwater was added to the obtained organic layer and the obtained mixturewas stirred at 23 degree C. for 30 minutes, followed by separating anorganic layer to wash with water. The washing step was conducted sixtimes. The washed organic layer was concentrated to obtain 28.24 partsof the compound represented by formula (I-12-e).

Into a reactor, 28.23 parts of the compound represented by the formula(I-12-e), 145 parts of tetrahydrofuran, 7.54 parts of pyridine and 0.97parts of dimethylaminopyridine were charged, and then 13.47 parts of thecompound represented by the formula (I-12-f) was added thereto andstirred at 23 degree C. for 18 hours. Then, 290 parts of n-heptane wasadded to the resulting solution, and then 70 parts of 5% hydrochloricacid was added, and the mixture was stirred 23 degree C. for 30 minutes.Then, the mixture was left still to separate an organic layer. 145 partsof ion exchanged water was added to the obtained organic layer and theobtained mixture was stirred at 23 degree C. for 30 minutes, followed byseparating an organic layer to wash with water. The washing step wasconducted six times. The washed organic layer was concentrated andpurified with column chromatography [silica gel 60N spherical shape,neutral, 100-210 μm, solvent: mixture of n-heptane and ethyl acetate(weight ratio 10/1), manufactured by Kanto Chem. Ltd.] to obtain 28.73parts of the compound represented by formula (I-12).

MS (mass spectrography): 516.1 (molecular ion peak)

Example 3: Synthesis of a Compound Represented by the Formula (I-15)

Into a reactor, 21.2 parts of the compound represented by the formula(I-15-a), 106 parts of chloroform, 6.98 parts of pyridine, 1.96 parts ofdimethylaminopyridine, 12.80 parts of the compound represented by theformula (I-15-b) and 16.91 parts of the compound represented by theformula (I-1-c) were charged and stirred at 23 degree C. for 5 hours.Then, 350 parts of chloroform was added to the resulting solution, andthen 65 parts of 5% hydrochloric acid was added, and the mixture wasstirred 23 degree C. for 30 minutes. Then, the mixture was left still toseparate an organic layer. 170 parts of ion exchanged water was added tothe obtained organic layer and the obtained mixture was stirred at 23degree C. for 30 minutes, followed by separating an organic layer towash with water. The washing step was conducted six times. The washedorganic layer was concentrated and purified with column chromatography[silica gel 60N spherical shape, neutral, 100-210 μm, solvent: mixtureof n-heptane and ethyl acetate (weight ratio 10/1), manufactured byKanto Chem. Ltd.] to obtain 22.12 parts of the compound represented byformula (I-15).

MS (mass spectrography): 414.1 (molecular ion peak)

Example 4: Synthesis of a Compound Represented by the Formula (I-3)

Into a reactor, 21.2 parts of the compound represented by the formula(I-1-a), 100 parts of chloroform, 6.98 parts of pyridine, 1.96 parts ofdimethylaminopyridine, 15.24 parts of the compound represented by theformula (I-3-b) and 16.91 parts of the compound represented by theformula (I-1-c) were charged and stirred at 23 degree C. for 5 hours.Then, 350 parts of chloroform was added to the resulting solution, andthen 65 parts of 5% hydrochloric acid was added, and the mixture wasstirred 23 degree C. for 30 minutes. Then, the mixture was left still toseparate an organic layer. 170 parts of ion exchanged water was added tothe obtained organic layer and the obtained mixture was stirred at 23degree C. for 30 minutes, followed by separating an organic layer towash with water. The washing step was conducted five times. The washedorganic layer was concentrated and purified with column chromatography[silica gel 60N spherical shape, neutral, 100-210 μm, solvent: mixtureof n-heptane and ethyl acetate (weight ratio 10/1), manufactured byKanto Chem. Ltd.] to obtain 24.22 parts of the compound represented byformula (I-3).

MS (mass spectrography): 446.1 (molecular ion peak)

Example 5: Synthesis of a Compound Represented by the Formula (I-10)

Into a reactor, 18.33 parts of the compound represented by the formula(I-1-a)), 50 parts of dimethylformamide, 4.79 parts of potassiumcarbonate and 1.15 parts of potassium iodide were charged and stirred,and then 28.35 parts of the compound represented by the formula (I-12-c)was added and stirred at 23 degree C. for 5 hours. Then, 200 parts ofchloroform was added to the resulting solution, and then 25 parts of 5%hydrochloric acid was added, and the mixture was stirred 23 degree C.for 30 minutes. Then, the mixture was left still to separate an organiclayer. 100 parts of ion exchanged water was added to the obtainedorganic layer and the obtained mixture was stirred at 23 degree C. for30 minutes, followed by separating an organic layer to wash with water.The washing step was conducted five times. The washed organic layer wasconcentrated to obtain 23.24 parts of the compound represented byformula (I-10).

MS (mass spectrography): 568.2 (molecular ion peak)

Synthesis Example 1: Synthesis of a Salt Represented by the Formula(B1-5)

In to a reactor, 50.49 parts of compound represented by formula (B1-5-a)and 252.44 parts of chloroform were mixed and stirred at 23 degree C.for 30 minutes. Then 16.27 parts of compound represented by formula(B1-5-b) were dropped thereinto and the obtained mixture was stirred at23 degree C. for one hour to obtain a solution containing the compoundrepresented by formula (B1-5-c).

To the obtained solution, 48.80 parts of compound represented by formula(B1-5-d) and 84.15 parts of ion-exchanged water were added and theobtained mixture was stirred at 23 degree C. for 12 hours. From theobtained solution which had two layers, the chloroform layer wascollected and then 84.15 parts of ion-exchanged water were added forwashing. The washing step was conducted five times. To the washedchloroform layer, 3.88 parts of active carbon were added and theobtained mixture was stirred, followed by filtrating. The collectedfiltrate was concentrated and then 125.87 parts of acetonitrile wereadded thereto and the obtained mixture was stirred, followed by beingconcentrated. 20.62 parts of acetonitrile and 309.30 parts oftert-butylmethylether were added to the obtained residues, followed bybeing stirred at 23 degree C. for about 30 minutes. Then the supernatantwas removed therefrom, and the residues were concentrated. To theconcentrated residues, 200 parts of n-heptane were added and theobtained mixture was stirred at 23 degree C. for about 30 minutes,followed by being filtrated to obtain 61.54 parts of salt represented byformula (B1-5).

MASS(ESI(+)Spectrum):M⁺375.2

MASS(ESI(−)Spectrum):M⁻339.1

Synthesis Example 2: Synthesis of a Salt Represented by the Formula(B1-21)

The compound represented by formula (B1-21-b) was produced according toa method recited in JP2008-209917A1.

30.00 parts of compound represented by formula (B1-21-b) and 35.50 partsof salt represented by formula (B1-21-a), 100 parts of chloroform and 50parts of ion exchanged water were mixed and stirred at 23 degree C. forabout 15 hours. The obtained reaction mixture, which had two layers, wasseparated into a chloroform layer therefrom. To the chloroform layer, 30parts of ion exchanged water was added and washed with it. These stepswere conducted five times. Then the washed layer was concentrated, andthen, 100 parts of tert-butylmethylether was added to the obtainedresidues and the obtained mixture was stirred at 23 degree C. for about30 minutes. The resulting mixture was filtrated to obtain 48.57 parts ofsalt represented by formula (B1-21-c).

20.00 parts of salt represented by formula (B1-21-c), 2.84 parts ofcompound represented by formula (B1-21-d) and 250 parts ofmonochlorobenzene were mixed and stirred at 23 degree C. for 30 minutes.To the resulting mixture, 0.21 parts of copper (II) dibenzoate was addedand the obtained mixture was stirred at 100 degree C. for 1 hour. Thereaction mixture was concentrated, and then, 200 parts of chloroform and50 parts of ion exchanged water were added to the obtained residues andthe obtained mixture was stirred at 23 degree C. for 30 minutes,followed by being separated into an organic layer therefrom. Thefollowing washing step was conducted five times. 50 parts of ionexchanged water were added to the obtained organic layer, and theobtained mixture was stirred at 23 degree C. for 30 minutes, followed bybeing separated into an organic layer. The obtained organic layer wasconcentrated, and then the obtained residues were dissolved in 53.51parts of acetonitrile. Then the mixture was concentrated, and then113.05 parts of tert-butylmethylether was added thereto and the obtainedmixture was stirred, followed by filtrating it to obtain 10.47 parts ofsalt represented by formula (B1-21).

MASS(ESI(+)Spectrum):M^(|)237.1

MASS(ESI(−)Spectrum):M⁻339.1

Synthesis Example 3: Synthesis of a Salt Represented by the Formula(B1-22)

11.26 parts of salt represented by formula (B1-21-a), 10 parts ofcompound represented by formula (B1-22-b), 50 parts of chloroform and 25parts of ion exchanged water were mixed and stirred at 23 degree C. forabout 15 hours. The obtained reaction mixture, which had two layers, wasseparated into a chloroform layer therefrom. To the chloroform layer, 15parts of ion exchanged water were added and washed with it: These stepswere conducted five times. Then the washed layer was concentrated, andthen, 50 parts of tert-butylmethylether was added to the obtainedresidues and the obtained mixture was stirred at 23 degree C. for about30 minutes. The resulting mixture was filtrated to obtain 11.75 parts ofsalt represented by formula (B1-22-c).

11.71 parts of salt represented by formula (B1-22-c), 1.7 parts ofcompound represented by formula (B1-22-d) and 46.84 parts ofmonochlorobenzene were mixed and stirred at 23 degree C. for 30 minutes.To the resulting mixture, 0.12 parts of copper (II) dibenzoate was addedand the obtained mixture was stirred at 100 degree C. for 30 minutes.The reaction mixture was concentrated, and then, to the obtainedresidues, 50 parts of chloroform and 12.5 parts of ion exchanged waterwere added and the obtained mixture was stirred at 23 degree C. for 30minutes, followed by being separated into an organic layer therefrom.12.5 parts of ion exchanged water was added to the obtained organiclayer and the obtained mixture was stirred at 23 degree C. for 30minutes, followed by being separated into an organic layer therefrom.The washing step was conducted eight times. Then the mixture wasconcentrated, and then 50 parts of tert-butylmethylether were addedthereto and the obtained mixture was stirred, followed by filtrating itto obtain 6.84 parts of salt represented by formula (B1-22).

MASS(ESI(+)Spectrum):M⁺237.1

MASS(ESI(−)Spectrum):M⁻323.0

Synthetic Example of the Resin

The monomers used for Synthesis of resins are shown below. Thesemonomers are referred to as “monomer (X)” where “(X)” is the symbol ofthe formula representing the structure of each monomer.

Synthesis Example 4: Synthesis of Resin A1

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-3) and monomer(a3-4-2) were mixed together with the mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-3) and monomer (a3-4-2)=45:14:2.5:38.5,and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reacted mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was dissolved in another propylene glycol monomethylether acetateto obtain a solution, and the solution was poured into a large amount ofa mixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated two times to obtainthe copolymer having a weight average molecular weight of about 7600 in68% yield. This resin, which had the structural units of the followingformulae, was referred to as Resin A1.

Synthesis Example 5: Synthesis of Resin A2

Monomer (a1-1-2), monomer (a1-2-3), monomer (a2-1-1), monomer (a3-2-3)and monomer (a3-1-1) were mixed together with the mole ratio of monomer(a1-1-2), monomer (a1-2-3), monomer (a2-1-1), monomer (a3-2-3) andmonomer (a3-1-1)=32:7:8:10:43, and propylene glycol monomethyletheracetate was added thereto in the amount equal to 1.5 times by mass ofthe total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.95% by mole and 2.85%by mole respectively with respect to the total amount of monomers, andthe resultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 8900 in 70% yield. This resin, whichhad the structural units of the following formula, was referred to ResinA2.

Example 6: Synthesis of Resin X1

Monomer (I-1) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 14000 in 75%yield. This resin, which had the structural units of the followingformula, was referred to as Resin X1.

Example 7: Synthesis of Resin X2

Monomer (I-12) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 14000 in 70%yield. This resin, which had the structural units of the followingformula, was referred to Resin X2.

Example 8: Synthesis of Resin X3

Monomer (I-1) and monomer (ax) were mixed together with the mole ratioof monomer (I-1) and monomer (ax)=45:55, and propylene glycolmonomethylether acetate was added thereto in the amount equal to 1.5times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.7% by mole and 2.1% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 14000 in 74% yield. This resin, whichhad the structural units of the following formulae, was referred toResin X3.

Example 9: Synthesis of Resin X4

Monomer (I-15) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 13000 in 75%yield. This resin, which had the structural units of the followingformula, was referred to Resin X4.

Example 10: Synthesis of Resin X5

Monomer (I-15) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-15) and monomer (a5-1-1)=50:50, and propylene glycolmonomethylether acetate was added thereto in the amount equal to 1.5times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.7% by mole and 2.1% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 13000 in 78% yield. This resin, whichhad the structural units of the following formulae, was referred toResin X5.

Example 11: Synthesis of Resin X6

Monomer (I-15) and monomer (a5-1-20) were mixed together with the moleratio of monomer (I-15) and monomer (a5-1-20)=50:50, and propyleneglycol monomethylether acetate was added thereto in the amount equal to1.5 times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.7% by mole and 2.1% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 14000 in 73% yield. This resin, whichhad the structural units of the following formulae, was referred toResin X6.

Example 12: Synthesis of Resin X7

Monomer (I-3) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thepolymer having a weight average molecular weight of about 15000 in 82%yield. This resin, which had the structural units of the followingformula, was referred to Resin X7.

Example 13: Synthesis of Resin X8

Monomer (I-10) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thepolymer having a weight average molecular weight of about 14000 in 69%yield. This resin, which had the structural units of the followingformula, was referred to Resin X8.

Example 14: Synthesis of Resin X9

Monomer (I-15) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added to the solution asinitiators in the amounts of 0.8% by mole and 2.4% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate a resin. The obtained resinwas filtrated. These operations were repeated twice to obtain thepolymer having a weight average molecular weight of about 11000 in 77%yield. This resin, which had the structural units of the followingformula, was referred to Resin X9.

Example 15: Synthesis of Resin X10

Monomer (I-15) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.9% by mole and 2.7% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was dissolved in another propylene glycol monomethylether acetate to obtain a solution, and the solution was poured into amixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice, resulting in77% yield of Resin X10 having a weight average molecular weight of about9100. This resin, which had the structural units of the followingformula, was referred to Resin X10.

Example 16: Synthesis of Resin X11

Monomer (I-15) was used, and propylene glycol monomethyl ether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reacted mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was dissolved in another propylene glycol monomethyl ether acetateto obtain a solution, and the solution was poured into a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. These operations were repeated twice to obtain the polymerhaving a weight average molecular weight of about 7400 in 75% yield.This resin, which had the structural units of the following formula, wasreferred to Resin X11.

Example 17: Synthesis of Resin X12

Monomer (I-15) and monomer (a4-0-12) were mixed together with the moleratio of monomer (I-15) and monomer (a4-0-12)=50:50, and propyleneglycol monomethylether acetate was added thereto in the amount equal to1.5 times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.9% by mole and 2.7% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 9200 in 82% yield. This resin, whichhad the structural units of the following formulae, was referred toResin X12.

Example 18: Synthesis of Resin X13

Monomer (I-15), monomer (a4-0-12) and monomer (a5-1-1) were mixedtogether with the mole ratio of monomer (I-15), monomer (a4-0-12) andmonomer (a5-1-1)=25:25:50, and propylene glycol monomethylether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.9% by mole and 2.7% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactedmixture was poured into a large amount of a mixture of methanol and ionexchanged water (4/1) to precipitate a resin. The obtained resin wasfiltrated to obtain the copolymer having a weight average molecularweight of about 9000 in 78% yield. This resin, which had the structuralunits of the following formulae, was referred to Resin X13.

Synthesis Example 6: Synthesis of Resin Xx1

Monomer (IX) and monomer (ax) were mixed together with the mole ratio ofmonomer (IX) and monomer (ax)=45:55, and propylene glycolmonomethylether acetate was added thereto in the amount equal to 1.5times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.7% by mole and 2.1% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reacted mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water (4/1) to precipitate a resin. Theobtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 15000 in 80% yield. This resin, whichhad the structural units of the following formulae, was referred toResin Xx1.

(Preparing Resist Composition)

Resist compositions were prepared by mixing and dissolving each of thecomponents shown in Table 1, and then filtrating through a fluororesinfilter having 0.2 μm pore diameter. After preserving the prepared resistcompositions at 30° C. for three weeks, the evaluations described laterwere carried out.

TABLE 1 Resin Acid Generator Weak Acid Inner Salt PB/PEB Resist Comp.(parts) (B) (parts) (D) (parts) (° C./° C.) Composition 1 X1/A1 = 0.7/10B1-21/B1-22 = D1 = 0.28 90/85 0.9/0.4 Composition 2 X2/A1 = 0.7/10B1-21/B1-22 = D1 = 0.28 90/85 0.9/0.4 Composition 3 X1/A1 = 0.7/10B1-5/B1-22 = D1 = 0.28 90/85 0.4/0.4 Composition 4 X3/A1 = 0.7/10B1-21/B1-22 = D1 = 0.28 90/85 0.9/0.4 Composition 5 X3/A2 = 0.7/10B1-21/B1-22 = D1 = 0.28 110/105 0.9/0.4 Composition 6 X3/A2 = 0.7/10B1-3 = 1.0 D1 = 0.28 110/105 Composition 7 X4/A1 = 0.7/10 B1-21/B1-22 =D1 = 0.28 90/85 0.9/0.4 Composition 8 X5/A1 = 0.7/10 B1-21/B1-22 = D1 =0.28 90/85 0.9/0.4 Composition 9 X6/A1 = 0.7/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 10 X4/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 11 X7/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 12 X8/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 13 X9/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 14 X10/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 15 X11/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 16 X12/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Composition 17 X13/A1 = 0.4/10 B1-21/B1-22 = D1 = 0.2890/85 0.9/0.4 Comparative Xx1/A2 = 0.7/10 B1-3 = 1.0 D1 = 0.28 110/105Composition 1<Resin>

A1, A2, X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13,Xx1:Resin A1, Resin A2, Resin X1, Resin X2, Resin X3, Resin X4, ResinX5, Resin X6, Resin X7, Resin X8, Resin X9, Resin X10, Resin X11, ResinX12, Resin X13, Resin Xx1, prepared by the above Synthesis of Resin.

<Acid Generator>

B1-3: The following salt, prepared by a method according to the methoddescribed in the Examples of JP2010-152341A

B1-5: Salt represented by the formula (B1-5)

B1-21: Salt represented by the formula (B1-21)

B1-22: Salt represented by the formula (B1-22)

<Weakly Acidic Inner Salt (D)>

D1: The following compound, Products of Tokyo Chemical Industry Co., LTD

<Solvent of Resist Composition>

Propyleneglycolmonomethylether acetate 265 parts Propyleneglycolmonomethylether 20 parts 2-Heptanone 20 partsγ-butyrolactone 3.5 parts <Producing Negative Resist Patterns>

A composition for an organic antireflective film (“ARC-29”, by NissanChemical Co. Ltd.) was applied onto 12-inch silicon wafers and baked for60 seconds at 205° C. to form a 78 nm thick organic antireflective film.

On one of the treated wafers, one of the resist compositions was thenapplied thereon by spin coating in such a manner that the thickness ofthe film after drying (pre-baking) became 100 nm.

The obtained wafer was then pre-baked for 60 sec on a direct hot plateat the temperature given in the “PB” column in Table 1.

On the wafer on which the resist film had thus been formed, the film wasexposed through a mask for forming 1:1 Line and space patterns (pitch 70to 100 nm/line width 35 to 50 nm) with changing exposure quantitystepwise using an ArF excimer laser stepper for immersion lithography(“XT:1900Gi” by ASML Ltd.: Na=1.35, Annular σ_(out)=0.85 σ_(in)=0.65XY-pol). Ultrapure water was used for medium of immersion.

After the exposure, post-exposure baking was carried out for 60 secondsat the temperature given in the “PEB” column in Table 1.

Then, development was carried out with butyl acetate (obtained fromTokyo Chemical Industry Co., LTD) at 23 degree C. for 20 seconds in themanner of dynamic dispensing method to obtain negative resist patterns.

Effective sensitivity was represented as the exposure quantity at whichline and space patterns with 50 nm of line width was resolved byexposure.

<Evaluation of Defects>

Each of the above-mentioned resist compositions was applied on a12-inch-silicon wafer by spin coating in such a manner that thethickness of the resulting film after drying became 150 nm.

The obtained wafer was then pre-baked for 60 seconds on a direct hotplate at the temperature given in the “PB” column in Table 1 to obtain acomposition layer.

The thus obtained wafer with the produced composition layer was rinsedwith water for 60 seconds using a developing apparatus (ACT-12, Tokyoelectron Co. Ltd.).

Thereafter, the number of defects was counted using a defect inspectionapparatus (KLA-2360, KLA-Tencor Co. Ltd.)

Table 2 illustrates the results thereof.

<Evaluation of Resolution>

A resist pattern produced where exposure was conducted at the exposurequantity equivalent to effective sensitivity was observed with ascanning electron microscope.

In Table 2, a “∘ ∘” was given when the resist pattern with the linewidth being 43 nm or less was resolved,

a “∘” was given when the resist pattern with the line width being frommore than 43 nm to less than 48 nm was resolved,

a “×” was given when only the resist pattern with the line width beingmore than 48 nm was resolved or when the resolved resist pattern has 48nm or less of the line width with a rounded or skirt shape in the top ofits profile or with the pattern collapse, and

Table 2 illustrates the results thereof. The number in parenthesesrepresents the minimum line width values of the resolved pattern withoutdefects.

TABLE 2 Resist Composition Defects Resolution Ex. 19 Composition 1 230∘∘ (43 nm) Ex. 20 Composition 2 370 ∘∘ (43 nm) Ex. 21 Composition 3 270∘ (44 nm) Ex. 22 Composition 4 480 ∘ (45 nm) Ex. 23 Composition 5 790 ∘(46 nm) Ex. 24 Composition 6 880 ∘ (46 nm) Ex. 25 Composition 7 150 ∘∘(42 nm) Ex. 26 Composition 8 180 ∘∘ (43 nm) Ex. 27 Composition 9 170 ∘∘(43 nm) Ex. 28 Composition 10 180 ∘∘ (41 nm) Ex. 29 Composition 11 210∘∘ (43 nm) Ex. 30 Composition 12 200 ∘∘ (43 nm) Ex. 31 Composition 13180 ∘∘ (41 nm) Ex. 32 Composition 14 170 ∘∘ (41 nm) Ex. 33 Composition15 180 ∘∘ (40 nm) Ex. 34 Composition 16 180 ∘∘ (41 nm) Ex. 35Composition 17 190 ∘∘ (41 nm) Comparative Comparative 2200 × (50 nm) Ex.1 Composition 1

The resin including a structural unit derived from the compound of thedisclosure is useful for resist compositions. A resist composition whichincludes the resin shows satisfactory storage stability, specificallyshows excellent resolution and less defects in the obtained resistpattern even after storage. Therefore, the resist composition can beused for semiconductor microfabrication.

The invention claimed is:
 1. A compound represented by formula (I),

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom; R² represents —(CH₂)_(n)—R^(f)or —CH(R^(fa))(R^(fb)), where n represents an integer of 1 to 6, andR^(f), R^(fa) and R^(fb) each independently represent a C₁ to C₆perfuloroalkyl group; represents a C₅ to C₁₈ divalent alicyclichydrocarbon group; A¹ and A² each independently represent a single bondor *-A³-X¹-(A⁴-X²)_(a)—; A³ and A⁴ each independently represent a C₁ toC₆ alkanediyl group; X¹ and X² each independently represents —O—, —CO—O—or —O—CO—; a represents 0 or 1; and * represents a binding site to anoxygen atom.
 2. The compound according to claim 1, wherein W¹ is anadamantanediyl group or a cyclohexanediyl group.
 3. The compoundaccording to claim 2, wherein the adamantanediyl group is any one of thegroups represented by formulae (Ad-1) to (Ad-3);

wherein one of * is a binding site to A¹ and another * is a binding siteto a carbonyl group.
 4. The compound according to claim 1, wherein A¹ isa single bond.
 5. The compound according to claim 1, wherein R² is—(CH₂)_(n)—R^(f), where n represents an integer of 1 to 6, and R^(f)represents a C₁ to C₆ perfluoroalkyl group.
 6. The compound according toclaim 1, wherein R² is —CH(R^(fa))(R^(fb)); where R^(Fa) and R^(fb) eachindependently represent a C₁ to C₆ perfluoroalkyl group, provided thatR^(Fa) and R^(fb) have 11 or less of carbon atoms in total.
 7. Acompound represented by formula (I′):

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom; R² represents —(CH₂)_(n)—R^(f)where n represents an integer of 2 to 6, and R^(f) represents a C₁ to C₆perfluoroalkyl group; represents a cyclopentanediyl group, acyclohexanediyl group, an adamantanediyl group, or a norbornanediylgroup; A¹ and A² each independently represent a single bond or*-A³-X¹-(A⁴-X²)_(a)—; A³ and A⁴ each independently represent a C₁ to C₆alkanediyl group; X¹ and X² each independently represents —O—, —CO—O— or—O—CO—; a represents 0 or 1; and * represents a binding site to anoxygen atom.